Rename auto fan pins and add auto fan flags

Marlin/Conditionals_post.h

   #define HAS_HEATER_2 (PIN_EXISTS(HEATER_2))
   #define HAS_HEATER_3 (PIN_EXISTS(HEATER_3))
   #define HAS_HEATER_BED (PIN_EXISTS(HEATER_BED))
-  #define HAS_AUTO_FAN_0 (PIN_EXISTS(EXTRUDER_0_AUTO_FAN))
-  #define HAS_AUTO_FAN_1 (PIN_EXISTS(EXTRUDER_1_AUTO_FAN))
-  #define HAS_AUTO_FAN_2 (PIN_EXISTS(EXTRUDER_2_AUTO_FAN))
-  #define HAS_AUTO_FAN_3 (PIN_EXISTS(EXTRUDER_3_AUTO_FAN))
-  #define AUTO_1_IS_0 (EXTRUDER_1_AUTO_FAN_PIN == EXTRUDER_0_AUTO_FAN_PIN)
-  #define AUTO_2_IS_0 (EXTRUDER_2_AUTO_FAN_PIN == EXTRUDER_0_AUTO_FAN_PIN)
-  #define AUTO_2_IS_1 (EXTRUDER_2_AUTO_FAN_PIN == EXTRUDER_1_AUTO_FAN_PIN)
-  #define AUTO_3_IS_0 (EXTRUDER_3_AUTO_FAN_PIN == EXTRUDER_0_AUTO_FAN_PIN)
-  #define AUTO_3_IS_1 (EXTRUDER_3_AUTO_FAN_PIN == EXTRUDER_1_AUTO_FAN_PIN)
-  #define AUTO_3_IS_2 (EXTRUDER_3_AUTO_FAN_PIN == EXTRUDER_2_AUTO_FAN_PIN)
+  #define HAS_AUTO_FAN_0 (PIN_EXISTS(E0_AUTO_FAN))
+  #define HAS_AUTO_FAN_1 (HOTENDS > 1 && PIN_EXISTS(E1_AUTO_FAN))
+  #define HAS_AUTO_FAN_2 (HOTENDS > 2 && PIN_EXISTS(E2_AUTO_FAN))
+  #define HAS_AUTO_FAN_3 (HOTENDS > 3 && PIN_EXISTS(E3_AUTO_FAN))
   #define HAS_AUTO_FAN (HAS_AUTO_FAN_0 || HAS_AUTO_FAN_1 || HAS_AUTO_FAN_2 || HAS_AUTO_FAN_3)
+  #define AUTO_1_IS_0 (E1_AUTO_FAN_PIN == E0_AUTO_FAN_PIN)
+  #define AUTO_2_IS_0 (E2_AUTO_FAN_PIN == E0_AUTO_FAN_PIN)
+  #define AUTO_2_IS_1 (E2_AUTO_FAN_PIN == E1_AUTO_FAN_PIN)
+  #define AUTO_3_IS_0 (E3_AUTO_FAN_PIN == E0_AUTO_FAN_PIN)
+  #define AUTO_3_IS_1 (E3_AUTO_FAN_PIN == E1_AUTO_FAN_PIN)
+  #define AUTO_3_IS_2 (E3_AUTO_FAN_PIN == E2_AUTO_FAN_PIN)
   #define HAS_FAN0 (PIN_EXISTS(FAN))
-  #define HAS_FAN1 (PIN_EXISTS(FAN1) && CONTROLLERFAN_PIN != FAN1_PIN && EXTRUDER_0_AUTO_FAN_PIN != FAN1_PIN && EXTRUDER_1_AUTO_FAN_PIN != FAN1_PIN && EXTRUDER_2_AUTO_FAN_PIN != FAN1_PIN && EXTRUDER_3_AUTO_FAN_PIN != FAN1_PIN)
-  #define HAS_FAN2 (PIN_EXISTS(FAN2) && CONTROLLERFAN_PIN != FAN2_PIN && EXTRUDER_0_AUTO_FAN_PIN != FAN2_PIN && EXTRUDER_1_AUTO_FAN_PIN != FAN2_PIN && EXTRUDER_2_AUTO_FAN_PIN != FAN2_PIN && EXTRUDER_3_AUTO_FAN_PIN != FAN2_PIN)
+  #define HAS_FAN1 (PIN_EXISTS(FAN1) && CONTROLLERFAN_PIN != FAN1_PIN && E0_AUTO_FAN_PIN != FAN1_PIN && E1_AUTO_FAN_PIN != FAN1_PIN && E2_AUTO_FAN_PIN != FAN1_PIN && E3_AUTO_FAN_PIN != FAN1_PIN)
+  #define HAS_FAN2 (PIN_EXISTS(FAN2) && CONTROLLERFAN_PIN != FAN2_PIN && E0_AUTO_FAN_PIN != FAN2_PIN && E1_AUTO_FAN_PIN != FAN2_PIN && E2_AUTO_FAN_PIN != FAN2_PIN && E3_AUTO_FAN_PIN != FAN2_PIN)
   #define HAS_CONTROLLERFAN (PIN_EXISTS(CONTROLLERFAN))
   #define HAS_SERVOS (defined(NUM_SERVOS) && NUM_SERVOS > 0)
   #define HAS_SERVO_0 (PIN_EXISTS(SERVO0))

Marlin/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/SanityCheck.h

  */
 #if HAS_AUTO_FAN
   #if HAS_FAN0
-    #if EXTRUDER_0_AUTO_FAN_PIN == FAN_PIN
-      #error "You cannot set EXTRUDER_0_AUTO_FAN_PIN equal to FAN_PIN."
-    #elif EXTRUDER_1_AUTO_FAN_PIN == FAN_PIN
-      #error "You cannot set EXTRUDER_1_AUTO_FAN_PIN equal to FAN_PIN."
-    #elif EXTRUDER_2_AUTO_FAN_PIN == FAN_PIN
-      #error "You cannot set EXTRUDER_2_AUTO_FAN_PIN equal to FAN_PIN."
-    #elif EXTRUDER_3_AUTO_FAN_PIN == FAN_PIN
-      #error "You cannot set EXTRUDER_3_AUTO_FAN_PIN equal to FAN_PIN."
+    #if E0_AUTO_FAN_PIN == FAN_PIN
+      #error "You cannot set E0_AUTO_FAN_PIN equal to FAN_PIN."
+    #elif E1_AUTO_FAN_PIN == FAN_PIN
+      #error "You cannot set E1_AUTO_FAN_PIN equal to FAN_PIN."
+    #elif E2_AUTO_FAN_PIN == FAN_PIN
+      #error "You cannot set E2_AUTO_FAN_PIN equal to FAN_PIN."
+    #elif E3_AUTO_FAN_PIN == FAN_PIN
+      #error "You cannot set E3_AUTO_FAN_PIN equal to FAN_PIN."
     #endif
   #endif
 #endif
 #endif
 
 #if HAS_CONTROLLERFAN
-  #if EXTRUDER_0_AUTO_FAN_PIN == CONTROLLERFAN_PIN
-    #error "You cannot set EXTRUDER_0_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
-  #elif EXTRUDER_1_AUTO_FAN_PIN == CONTROLLERFAN_PIN
-    #error "You cannot set EXTRUDER_1_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
-  #elif EXTRUDER_2_AUTO_FAN_PIN == CONTROLLERFAN_PIN
-    #error "You cannot set EXTRUDER_2_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
-  #elif EXTRUDER_3_AUTO_FAN_PIN == CONTROLLERFAN_PIN
-    #error "You cannot set EXTRUDER_3_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
+  #if E0_AUTO_FAN_PIN == CONTROLLERFAN_PIN
+    #error "You cannot set E0_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
+  #elif E1_AUTO_FAN_PIN == CONTROLLERFAN_PIN
+    #error "You cannot set E1_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
+  #elif E2_AUTO_FAN_PIN == CONTROLLERFAN_PIN
+    #error "You cannot set E2_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
+  #elif E3_AUTO_FAN_PIN == CONTROLLERFAN_PIN
+    #error "You cannot set E3_AUTO_FAN_PIN equal to CONTROLLERFAN_PIN."
   #endif
 #endif
 

Marlin/example_configurations/Cartesio/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN 7
-#define EXTRUDER_1_AUTO_FAN_PIN 7
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+//#define E0_AUTO_FAN_PIN -1
+//#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 35
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/Felix/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/Hephestos/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/Hephestos_2/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN 11
-#define EXTRUDER_1_AUTO_FAN_PIN  6
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+//#define E0_AUTO_FAN_PIN -1
+//#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/K8200/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/K8400/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/RigidBot/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/SCARA/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/TAZ4/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/WITBOX/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/delta/biv2.5/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins.
+ * Override those here. Set to -1 to disable unused fans.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/delta/generic/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/delta/kossel_mini/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/delta/kossel_pro/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/delta/kossel_xl/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/makibox/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/example_configurations/tvrrug/Round2/Configuration_adv.h

 
 // @section extruder
 
-// Extruder cooling fans
-// Configure fan pin outputs to automatically turn on/off when the associated
-// extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
-// Multiple extruders can be assigned to the same pin in which case
-// the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN -1
-#define EXTRUDER_1_AUTO_FAN_PIN -1
-#define EXTRUDER_2_AUTO_FAN_PIN -1
-#define EXTRUDER_3_AUTO_FAN_PIN -1
+/**
+ * Extruder cooling fans
+ *
+ * Extruder auto fans automatically turn on when their extruders'
+ * temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE.
+ *
+ * Your board's pins file specifies the recommended pins. Override those here
+ * or set to -1 to disable completely.
+ *
+ * Multiple extruders can be assigned to the same pin in which case
+ * the fan will turn on when any selected extruder is above the threshold.
+ */
+#define E0_AUTO_FAN_PIN -1
+#define E1_AUTO_FAN_PIN -1
+#define E2_AUTO_FAN_PIN -1
+#define E3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 

Marlin/pins.h

   #endif
 #endif
 
-#define _H0_PINS HEATER_0_PIN, EXTRUDER_0_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_0_PIN),
+#define _H0_PINS HEATER_0_PIN, E0_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_0_PIN),
 #define _H1_PINS
 #define _H2_PINS
 #define _H3_PINS
 
 #if HOTENDS > 1
   #undef _H1_PINS
-  #define _H1_PINS HEATER_1_PIN, EXTRUDER_1_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_1_PIN),
+  #define _H1_PINS HEATER_1_PIN, E1_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_1_PIN),
   #if HOTENDS > 2
     #undef _H2_PINS
-    #define _H2_PINS HEATER_2_PIN, EXTRUDER_2_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_2_PIN),
+    #define _H2_PINS HEATER_2_PIN, E2_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_2_PIN),
     #if HOTENDS > 3
       #undef _H3_PINS
-      #define _H3_PINS HEATER_3_PIN, EXTRUDER_3_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_3_PIN),
+      #define _H3_PINS HEATER_3_PIN, E3_AUTO_FAN_PIN, marlinAnalogInputToDigitalPin(TEMP_3_PIN),
       #if HOTENDS > 4
         #undef _H4_PINS
         #define _H4_PINS HEATER_4_PIN, marlinAnalogInputToDigitalPin(TEMP_4_PIN),

Marlin/pinsDebug.h

   #if PIN_EXISTS(CONTROLLERFAN)
     PIN_SAY(CONTROLLERFAN_PIN);
   #endif
-  #if PIN_EXISTS(EXTRUDER_0_AUTO_FAN)
-    PIN_SAY(EXTRUDER_0_AUTO_FAN_PIN);
+  #if PIN_EXISTS(E0_AUTO_FAN)
+    PIN_SAY(E0_AUTO_FAN_PIN);
   #endif
-  #if PIN_EXISTS(EXTRUDER_1_AUTO_FAN)
-    PIN_SAY(EXTRUDER_1_AUTO_FAN_PIN);
+  #if PIN_EXISTS(E1_AUTO_FAN)
+    PIN_SAY(E1_AUTO_FAN_PIN);
   #endif
-  #if PIN_EXISTS(EXTRUDER_2_AUTO_FAN)
-    PIN_SAY(EXTRUDER_2_AUTO_FAN_PIN);
+  #if PIN_EXISTS(E2_AUTO_FAN)
+    PIN_SAY(E2_AUTO_FAN_PIN);
   #endif
-  #if PIN_EXISTS(EXTRUDER_3_AUTO_FAN)
-    PIN_SAY(EXTRUDER_3_AUTO_FAN_PIN);
+  #if PIN_EXISTS(E3_AUTO_FAN)
+    PIN_SAY(E3_AUTO_FAN_PIN);
   #endif
   #if PIN_EXISTS(HEATER_0)
     PIN_SAY(HEATER_0_PIN);

Marlin/pins_AZTEEG_X3_PRO.h

 #define CONTROLLERFAN_PIN   4 // Pin used for the fan to cool motherboard (-1 to disable)
 
 // Fans/Water Pump to cool the hotend cool side.
-#define EXTRUDER_0_AUTO_FAN_PIN   5
-#define EXTRUDER_1_AUTO_FAN_PIN   5
-#define EXTRUDER_2_AUTO_FAN_PIN   5
-#define EXTRUDER_3_AUTO_FAN_PIN   5
+#define E0_AUTO_FAN_PIN     5
+#define E1_AUTO_FAN_PIN     5
+#define E2_AUTO_FAN_PIN     5
+#define E3_AUTO_FAN_PIN     5
 
 //
 // LCD / Controller

Marlin/temperature.cpp

 #if HAS_AUTO_FAN
 
   void Temperature::checkExtruderAutoFans() {
-    const int8_t fanPin[] = { EXTRUDER_0_AUTO_FAN_PIN, EXTRUDER_1_AUTO_FAN_PIN, EXTRUDER_2_AUTO_FAN_PIN, EXTRUDER_3_AUTO_FAN_PIN };
+    const int8_t fanPin[] = { E0_AUTO_FAN_PIN, E1_AUTO_FAN_PIN, E2_AUTO_FAN_PIN, E3_AUTO_FAN_PIN };
     const int fanBit[] = {
                     0,
       AUTO_1_IS_0 ? 0 :               1,
   #endif
 
   #if HAS_AUTO_FAN_0
-    #if EXTRUDER_0_AUTO_FAN_PIN == FAN1_PIN
-      SET_OUTPUT(EXTRUDER_0_AUTO_FAN_PIN);
+    #if E0_AUTO_FAN_PIN == FAN1_PIN
+      SET_OUTPUT(E0_AUTO_FAN_PIN);
       #if ENABLED(FAST_PWM_FAN)
-        setPwmFrequency(EXTRUDER_0_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
+        setPwmFrequency(E0_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
       #endif
     #else
-      pinMode(EXTRUDER_0_AUTO_FAN_PIN, OUTPUT);
+      pinMode(E0_AUTO_FAN_PIN, OUTPUT);
     #endif
   #endif
   #if HAS_AUTO_FAN_1 && !AUTO_1_IS_0
-    #if EXTRUDER_1_AUTO_FAN_PIN == FAN1_PIN
-      SET_OUTPUT(EXTRUDER_1_AUTO_FAN_PIN);
+    #if E1_AUTO_FAN_PIN == FAN1_PIN
+      SET_OUTPUT(E1_AUTO_FAN_PIN);
       #if ENABLED(FAST_PWM_FAN)
-        setPwmFrequency(EXTRUDER_1_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
+        setPwmFrequency(E1_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
       #endif
     #else
-      pinMode(EXTRUDER_1_AUTO_FAN_PIN, OUTPUT);
+      pinMode(E1_AUTO_FAN_PIN, OUTPUT);
     #endif
   #endif
   #if HAS_AUTO_FAN_2 && !AUTO_2_IS_0 && !AUTO_2_IS_1
-    #if EXTRUDER_2_AUTO_FAN_PIN == FAN1_PIN
-      SET_OUTPUT(EXTRUDER_2_AUTO_FAN_PIN);
+    #if E2_AUTO_FAN_PIN == FAN1_PIN
+      SET_OUTPUT(E2_AUTO_FAN_PIN);
       #if ENABLED(FAST_PWM_FAN)
-        setPwmFrequency(EXTRUDER_2_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
+        setPwmFrequency(E2_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
       #endif
     #else
-      pinMode(EXTRUDER_2_AUTO_FAN_PIN, OUTPUT);
+      pinMode(E2_AUTO_FAN_PIN, OUTPUT);
     #endif
   #endif
   #if HAS_AUTO_FAN_3 && !AUTO_3_IS_0 && !AUTO_3_IS_1 && !AUTO_3_IS_2
-    #if EXTRUDER_3_AUTO_FAN_PIN == FAN1_PIN
-      SET_OUTPUT(EXTRUDER_3_AUTO_FAN_PIN);
+    #if E3_AUTO_FAN_PIN == FAN1_PIN
+      SET_OUTPUT(E3_AUTO_FAN_PIN);
       #if ENABLED(FAST_PWM_FAN)
-        setPwmFrequency(EXTRUDER_3_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
+        setPwmFrequency(E3_AUTO_FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
       #endif
     #else
-      pinMode(EXTRUDER_3_AUTO_FAN_PIN, OUTPUT);
+      pinMode(E3_AUTO_FAN_PIN, OUTPUT);
     #endif
   #endif