diff --git a/Marlin/src/pins/pins.h b/Marlin/src/pins/pins.h
index cdc4fdb7a406d..3e74509180e27 100644
--- a/Marlin/src/pins/pins.h
+++ b/Marlin/src/pins/pins.h
@@ -169,7 +169,7 @@
 #elif MB(MKS_GEN_13)
   #include "ramps/pins_MKS_GEN_13.h"                // ATmega2560, ATmega1280               env:mega2560 env:mega1280
 #elif MB(MKS_GEN_L)
-  #include "ramps/pins_MKS_GEN_L.h"                 // ATmega2560, ATmega1280               env:mega2560 env:mega1280
+  #include "ramps/pins_MKS_GEN_L.h"                 // ATmega2560                           env:mega2560
 #elif MB(KFB_2)
   #include "ramps/pins_BIQU_KFB_2.h"                // ATmega2560                           env:mega2560
 #elif MB(ZRIB_V20)
diff --git a/Marlin/src/pins/ramps/pins_MKS_GEN_L.h b/Marlin/src/pins/ramps/pins_MKS_GEN_L.h
index 73e7aa577d50c..4d4bee161f3a1 100644
--- a/Marlin/src/pins/ramps/pins_MKS_GEN_L.h
+++ b/Marlin/src/pins/ramps/pins_MKS_GEN_L.h
@@ -25,7 +25,8 @@
  * MKS GEN L – Arduino Mega2560 with RAMPS v1.4 pin assignments
  * Schematic: https://green-candy.osdn.jp/external/MarlinFW/board_schematics/RAMPS/MKS%20GEN%20L%20v1.0/MKS%20Gen_L%20V1.0_008%20SCH.pdf
  * Origin: https://github.com/makerbase-mks/MKS-GEN_L/blob/master/hardware/MKS%20Gen_L%20V1.0_008/MKS%20Gen_L%20V1.0_008%20SCH.pdf
- * ATmega2560, ATmega1280
+ * Note: Schematic contains pin & connector errors
+ * ATmega2560
  */
 
 #if HOTENDS > 2 || E_STEPPERS > 2
@@ -38,10 +39,15 @@
 // Heaters / Fans
 //
 
-#define MOSFET_A_PIN                          10  // HE0
-#define MOSFET_B_PIN                           7  // HE1 or FAN Hotend Cooling
-#define MOSFET_C_PIN                           8  // HBED
-#define FAN0_PIN                               9  // FAN Part Cooling
+#define HEATER_BED_PIN                         8  // H-BED
+#define HEATER_0_PIN                          10  // HE0
+#if ANY(HAS_MULTI_HOTEND, HEATERS_PARALLEL)
+  #define HEATER_1_PIN                         7  // HE1
+#else
+  #define FAN1_PIN                             7  // HE1
+#endif
+
+#define FAN0_PIN                               9  // FAN
 
 //
 // CS Pins wired to avoid conflict with the LCD
diff --git a/Marlin/src/pins/ramps/pins_RAMPS.h b/Marlin/src/pins/ramps/pins_RAMPS.h
index 0195f3a1bc9aa..5bbdf1f419cf7 100644
--- a/Marlin/src/pins/ramps/pins_RAMPS.h
+++ b/Marlin/src/pins/ramps/pins_RAMPS.h
@@ -231,16 +231,22 @@
   #define MOSFET_D_PIN                        -1
 #endif
 
-#define HEATER_0_PIN                MOSFET_A_PIN
+#ifndef HEATER_0_PIN
+  #define HEATER_0_PIN              MOSFET_A_PIN
+#endif
 
 #if FET_ORDER_EFB                                 // Hotend, Fan, Bed
   #ifndef HEATER_BED_PIN
     #define HEATER_BED_PIN          MOSFET_C_PIN
   #endif
 #elif FET_ORDER_EEF                               // Hotend, Hotend, Fan
-  #define HEATER_1_PIN              MOSFET_B_PIN
+  #ifndef HEATER_1_PIN
+    #define HEATER_1_PIN            MOSFET_B_PIN
+  #endif
 #elif FET_ORDER_EEB                               // Hotend, Hotend, Bed
-  #define HEATER_1_PIN              MOSFET_B_PIN
+  #ifndef HEATER_1_PIN
+    #define HEATER_1_PIN            MOSFET_B_PIN
+  #endif
   #ifndef HEATER_BED_PIN
     #define HEATER_BED_PIN          MOSFET_C_PIN
   #endif
@@ -253,9 +259,13 @@
     #define HEATER_BED_PIN          MOSFET_C_PIN
   #endif
   #if ANY(HAS_MULTI_HOTEND, HEATERS_PARALLEL)
-    #define HEATER_1_PIN            MOSFET_D_PIN
+    #ifndef HEATER_1_PIN
+      #define HEATER_1_PIN          MOSFET_D_PIN
+    #endif
   #else
-    #define FAN1_PIN                MOSFET_D_PIN
+    #ifndef FAN1_PIN
+      #define FAN1_PIN              MOSFET_D_PIN
+    #endif
   #endif
 #endif