[1.1.x] Update Thermal Protection Documentation (#8282)

* Fix thermal protection documentation.

Even before the recent thermal protection changes, the documentation of
the thermal protection feature in the config files did not match the
implementation.  I fixed the documentation and reconciled the M303
implementation with the documentation.

* Applied documentation changes to sample config files

* Renamed hysteresis to watch_temp_increase

* Added gcodes back into documentation.

Marlin/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/AlephObjects/TAZ4/Configuration.h

@@ -448,12 +448,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/AlephObjects/TAZ4/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/AliExpress/CL-260/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Anet/A6/Configuration.h

@@ -448,12 +448,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Anet/A6/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 60        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 10    // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 60                // Seconds
   #define WATCH_TEMP_INCREASE 5               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 5 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 180                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Anet/A8/Configuration.h

@@ -434,12 +434,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Anet/A8/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 60        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 10    // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 5 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 180               // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/BQ/Hephestos/Configuration.h

@@ -419,12 +419,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/BQ/Hephestos/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/BQ/Hephestos_2/Configuration.h

@@ -429,12 +429,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/BQ/Hephestos_2/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/BQ/WITBOX/Configuration.h

@@ -419,12 +419,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/BQ/WITBOX/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Cartesio/Configuration.h

@@ -427,12 +427,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Cartesio/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Creality/CR-10/Configuration.h

@@ -438,12 +438,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Creality/CR-10/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Felix/Configuration.h

@@ -409,12 +409,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Felix/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Felix/DUAL/Configuration.h

@@ -409,12 +409,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/FolgerTech/i3-2020/Configuration.h

@@ -433,12 +433,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/FolgerTech/i3-2020/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 2     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 40                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Geeetech/GT2560/Configuration.h

@@ -443,12 +443,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Geeetech/I3_Pro_X-GT2560/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Infitary/i3-M508/Configuration.h

@@ -432,12 +432,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Infitary/i3-M508/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Malyan/M150/Configuration.h

@@ -436,12 +436,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Malyan/M150/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Micromake/C1/basic/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Micromake/C1/enhanced/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Micromake/C1/enhanced/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/RigidBot/Configuration.h

@@ -424,12 +424,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/RigidBot/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/SCARA/Configuration.h

@@ -440,12 +440,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/SCARA/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Sanguinololu/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Sanguinololu/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/TinyBoy2/Configuration.h

@@ -478,12 +478,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/TinyBoy2/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Velleman/K8200/Configuration.h

@@ -458,12 +458,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Velleman/K8200/Configuration_adv.h

@@ -57,18 +57,20 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   // K8200 has weak heaters/power supply by default, so you have to relax!
@@ -76,13 +78,16 @@
   #define THERMAL_PROTECTION_HYSTERESIS 8     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   // K8200 has weak heaters/power supply by default, so you have to relax!
   #define WATCH_TEMP_PERIOD 30                // Seconds
@@ -99,13 +104,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 10 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Velleman/K8400/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/Velleman/K8400/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/Velleman/K8400/Dual-head/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/adafruit/ST7565/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/delta/FLSUN/auto_calibrate/Configuration.h

@@ -438,12 +438,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/delta/FLSUN/auto_calibrate/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/delta/FLSUN/kossel_mini/Configuration.h

@@ -438,12 +438,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/delta/FLSUN/kossel_mini/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/delta/generic/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/delta/generic/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/delta/kossel_mini/Configuration.h

@@ -428,12 +428,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/delta/kossel_mini/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/delta/kossel_pro/Configuration.h

@@ -414,12 +414,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/delta/kossel_pro/Configuration_adv.h

@@ -53,31 +53,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -91,13 +96,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/delta/kossel_xl/Configuration.h

@@ -432,12 +432,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/delta/kossel_xl/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/gCreate/gMax1.5+/Configuration.h

@@ -441,12 +441,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/gCreate/gMax1.5+/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 50        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 3     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 50                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/makibox/Configuration.h

@@ -431,12 +431,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/makibox/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/tvrrug/Round2/Configuration.h

@@ -417,12 +417,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/tvrrug/Round2/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/example_configurations/wt150/Configuration.h

@@ -433,12 +433,13 @@
 //===========================================================================
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * If you get "Thermal Runaway" or "Heating failed" errors the
  * details can be tuned in Configuration_adv.h

Marlin/example_configurations/wt150/Configuration_adv.h

@@ -48,31 +48,36 @@
 #endif
 
 /**
- * Thermal Protection protects your printer from damage and fire if a
- * thermistor falls out or temperature sensors fail in any way.
+ * Thermal Protection provides additional protection to your printer from damage
+ * and fire. Marlin always includes safe min and max temperature ranges which
+ * protect against a broken or disconnected thermistor wire.
  *
- * The issue: If a thermistor falls out or a temperature sensor fails,
- * Marlin can no longer sense the actual temperature. Since a disconnected
- * thermistor reads as a low temperature, the firmware will keep the heater on.
+ * The issue: If a thermistor falls out, it will report the much lower
+ * temperature of the air in the room, and the the firmware will keep
+ * the heater on.
  *
  * The solution: Once the temperature reaches the target, start observing.
- * If the temperature stays too far below the target (hysteresis) for too long (period),
- * the firmware will halt the machine as a safety precaution.
+ * If the temperature stays too far below the target (hysteresis) for too
+ * long (period), the firmware will halt the machine as a safety precaution.
  *
- * If you get false positives for "Thermal Runaway" increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
+ * If you get false positives for "Thermal Runaway", increase
+ * THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD
  */
 #if ENABLED(THERMAL_PROTECTION_HOTENDS)
   #define THERMAL_PROTECTION_PERIOD 40        // Seconds
   #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
 
   /**
-   * Whenever an M104 or M109 increases the target temperature the firmware will wait for the
-   * WATCH_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109,
-   * but only if the current temperature is far enough below the target for a reliable test.
+   * Whenever an M104, M109, or M303 increases the target temperature, the
+   * firmware will wait for the WATCH_TEMP_PERIOD to expire. If the temperature
+   * hasn't increased by WATCH_TEMP_INCREASE degrees, the machine is halted and
+   * requires a hard reset. This test restarts with any M104/M109/M303, but only
+   * if the current temperature is far enough below the target for a reliable
+   * test.
    *
-   * If you get false positives for "Heating failed" increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE
-   * WATCH_TEMP_INCREASE should not be below 2.
+   * If you get false positives for "Heating failed", increase WATCH_TEMP_PERIOD
+   * and/or decrease WATCH_TEMP_INCREASE. WATCH_TEMP_INCREASE should not be set
+   * below 2.
    */
   #define WATCH_TEMP_PERIOD 20                // Seconds
   #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
@@ -86,13 +91,7 @@
   #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
 
   /**
-   * Whenever an M140 or M190 increases the target temperature the firmware will wait for the
-   * WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn't increased by WATCH_BED_TEMP_INCREASE
-   * degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190,
-   * but only if the current temperature is far enough below the target for a reliable test.
-   *
-   * If you get too many "Heating failed" errors, increase WATCH_BED_TEMP_PERIOD and/or decrease
-   * WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be below 2.)
+   * As described above, except for the bed (M140/M190/M303).
    */
   #define WATCH_BED_TEMP_PERIOD 60                // Seconds
   #define WATCH_BED_TEMP_INCREASE 2               // Degrees Celsius

Marlin/temperature.cpp

@@ -240,20 +240,20 @@ uint8_t Temperature::soft_pwm_amount[HOTENDS],
       ;
       const int8_t watch_temp_period =
         #if ENABLED(THERMAL_PROTECTION_BED) && ENABLED(PIDTEMPBED) && ENABLED(THERMAL_PROTECTION_HOTENDS) && ENABLED(PIDTEMP)
-          hotend < 0 ? temp - THERMAL_PROTECTION_BED_PERIOD : THERMAL_PROTECTION_PERIOD
+          hotend < 0 ? WATCH_BED_TEMP_PERIOD : WATCH_TEMP_PERIOD
         #elif ENABLED(THERMAL_PROTECTION_BED) && ENABLED(PIDTEMPBED)
-          THERMAL_PROTECTION_BED_PERIOD
+          WATCH_BED_TEMP_PERIOD
         #else
-          THERMAL_PROTECTION_PERIOD
+          WATCH_TEMP_PERIOD
         #endif
       ;
-      const int8_t hysteresis =
+      const int8_t watch_temp_increase =
         #if ENABLED(THERMAL_PROTECTION_BED) && ENABLED(PIDTEMPBED) && ENABLED(THERMAL_PROTECTION_HOTENDS) && ENABLED(PIDTEMP)
-          hotend < 0 ? TEMP_BED_HYSTERESIS : TEMP_HYSTERESIS
+          hotend < 0 ? WATCH_BED_TEMP_INCREASE : WATCH_TEMP_INCREASE
         #elif ENABLED(THERMAL_PROTECTION_BED) && ENABLED(PIDTEMPBED)
-          TEMP_BED_HYSTERESIS
+          WATCH_BED_TEMP_INCREASE
         #else
-          TEMP_HYSTERESIS
+          WATCH_TEMP_INCREASE
         #endif
       ;
       millis_t temp_change_ms = next_temp_ms + watch_temp_period * 1000UL;
@@ -430,10 +430,12 @@ uint8_t Temperature::soft_pwm_amount[HOTENDS],
         #if WATCH_THE_BED || WATCH_HOTENDS
           if (!heated && input > next_watch_temp) {
             if (input > watch_temp_target) heated = true;
-            next_watch_temp = input + hysteresis;
+            next_watch_temp = input + watch_temp_increase;
             temp_change_ms = ms + watch_temp_period * 1000UL;
           }
-          else if ((!heated && ELAPSED(ms, temp_change_ms)) || (heated && input < temp - MAX_OVERSHOOT_PID_AUTOTUNE))
+          else if (!heated && ELAPSED(ms, temp_change_ms))
+            _temp_error(hotend, PSTR(MSG_T_HEATING_FAILED), PSTR(MSG_HEATING_FAILED_LCD));
+          else if (heated && input < temp - MAX_OVERSHOOT_PID_AUTOTUNE)
             _temp_error(hotend, PSTR(MSG_T_THERMAL_RUNAWAY), PSTR(MSG_THERMAL_RUNAWAY));
         #endif
       } // every 2 seconds