diff --git a/Marlin/src/HAL/AVR/inc/SanityCheck.h b/Marlin/src/HAL/AVR/inc/SanityCheck.h
index 15a5be4cd2..7936de8b99 100644
--- a/Marlin/src/HAL/AVR/inc/SanityCheck.h
+++ b/Marlin/src/HAL/AVR/inc/SanityCheck.h
@@ -25,6 +25,30 @@
  * Test AVR-specific configuration values for errors at compile-time.
  */
 
+/**
+ * Check for common serial pin conflicts
+ */
+#define CHECK_SERIAL_PIN(N) ( \
+     X_STOP_PIN == N || Y_STOP_PIN == N || Z_STOP_PIN == N \
+  || X_MIN_PIN  == N || Y_MIN_PIN  == N || Z_MIN_PIN  == N \
+  || X_MAX_PIN  == N || Y_MAX_PIN  == N || Z_MAX_PIN  == N \
+  || X_STEP_PIN == N || Y_STEP_PIN == N || Z_STEP_PIN == N \
+  || X_DIR_PIN  == N || Y_DIR_PIN  == N || Z_DIR_PIN  == N \
+  || X_ENA_PIN  == N || Y_ENA_PIN  == N || Z_ENA_PIN  == N \
+)
+#if CONF_SERIAL_IS(0) // D0-D1. No known conflicts.
+#endif 
+#if CONF_SERIAL_IS(1) && (CHECK_SERIAL_PIN(18) || CHECK_SERIAL_PIN(19))
+  #error "Serial Port 1 pin D18 and/or D19 conflicts with another pin on the board."
+#endif 
+#if CONF_SERIAL_IS(2) && (CHECK_SERIAL_PIN(16) || CHECK_SERIAL_PIN(17))
+  #error "Serial Port 2 pin D16 and/or D17 conflicts with another pin on the board."
+#endif
+#if CONF_SERIAL_IS(3) && (CHECK_SERIAL_PIN(14) || CHECK_SERIAL_PIN(15))
+  #error "Serial Port 3 pin D14 and/or D15 conflicts with another pin on the board."
+#endif 
+#undef CHECK_SERIAL_PIN
+
 /**
  * Checks for FAST PWM
  */
diff --git a/Marlin/src/HAL/DUE/inc/SanityCheck.h b/Marlin/src/HAL/DUE/inc/SanityCheck.h
index 75480acaf2..dd37a7bde1 100644
--- a/Marlin/src/HAL/DUE/inc/SanityCheck.h
+++ b/Marlin/src/HAL/DUE/inc/SanityCheck.h
@@ -25,6 +25,30 @@
  * Test Arduino Due specific configuration values for errors at compile-time.
  */
 
+/**
+ * Check for common serial pin conflicts
+ */
+#define CHECK_SERIAL_PIN(N) ( \
+     X_STOP_PIN == N || Y_STOP_PIN == N || Z_STOP_PIN == N \
+  || X_MIN_PIN  == N || Y_MIN_PIN  == N || Z_MIN_PIN  == N \
+  || X_MAX_PIN  == N || Y_MAX_PIN  == N || Z_MAX_PIN  == N \
+  || X_STEP_PIN == N || Y_STEP_PIN == N || Z_STEP_PIN == N \
+  || X_DIR_PIN  == N || Y_DIR_PIN  == N || Z_DIR_PIN  == N \
+  || X_ENA_PIN  == N || Y_ENA_PIN  == N || Z_ENA_PIN  == N \
+)
+#if CONF_SERIAL_IS(0) // D0-D1. No known conflicts.
+#endif 
+#if CONF_SERIAL_IS(1) && (CHECK_SERIAL_PIN(18) || CHECK_SERIAL_PIN(19))
+  #error "Serial Port 1 pin D18 and/or D19 conflicts with another pin on the board."
+#endif 
+#if CONF_SERIAL_IS(2) && (CHECK_SERIAL_PIN(16) || CHECK_SERIAL_PIN(17))
+  #error "Serial Port 2 pin D16 and/or D17 conflicts with another pin on the board."
+#endif
+#if CONF_SERIAL_IS(3) && (CHECK_SERIAL_PIN(14) || CHECK_SERIAL_PIN(15))
+  #error "Serial Port 3 pin D14 and/or D15 conflicts with another pin on the board."
+#endif 
+#undef CHECK_SERIAL_PIN
+
 /**
  * HARDWARE VS. SOFTWARE SPI COMPATIBILITY
  *
diff --git a/Marlin/src/pins/mega/pins_GT2560_V3_MC2.h b/Marlin/src/pins/mega/pins_GT2560_V3_MC2.h
index 6b22b4139b..e683d4dfda 100644
--- a/Marlin/src/pins/mega/pins_GT2560_V3_MC2.h
+++ b/Marlin/src/pins/mega/pins_GT2560_V3_MC2.h
@@ -27,9 +27,9 @@
 
 #define BOARD_INFO_NAME "GT2560 V3.0 (MC2)"
 
-#define X_MIN_PIN                            22
-#define X_MAX_PIN                            24
-#define Y_MIN_PIN                            26
-#define Y_MAX_PIN                            28
+#define X_MIN_PIN                             22
+#define X_MAX_PIN                             24
+#define Y_MIN_PIN                             26
+#define Y_MAX_PIN                             28
 
 #include "pins_GT2560_V3.h"
diff --git a/Marlin/src/pins/pins_postprocess.h b/Marlin/src/pins/pins_postprocess.h
index aabe0da858..1609c9c083 100644
--- a/Marlin/src/pins/pins_postprocess.h
+++ b/Marlin/src/pins/pins_postprocess.h
@@ -1319,6 +1319,9 @@
   #undef X_MAX_PIN
   #define X_MAX_PIN          -1
 #endif
+#if NONE(USE_XMIN_PLUG, USE_XMAX_PLUG)
+  #undef X_STOP_PIN
+#endif
 #if DISABLED(USE_YMIN_PLUG)
   #undef Y_MIN_PIN
   #define Y_MIN_PIN          -1
@@ -1327,6 +1330,9 @@
   #undef Y_MAX_PIN
   #define Y_MAX_PIN          -1
 #endif
+#if NONE(USE_YMIN_PLUG, USE_YMAX_PLUG)
+  #undef Y_STOP_PIN
+#endif
 #if DISABLED(USE_ZMIN_PLUG)
   #undef Z_MIN_PIN
   #define Z_MIN_PIN          -1
@@ -1335,6 +1341,9 @@
   #undef Z_MAX_PIN
   #define Z_MAX_PIN          -1
 #endif
+#if NONE(USE_ZMIN_PLUG, USE_ZMAX_PLUG)
+  #undef Z_STOP_PIN
+#endif
 #if DISABLED(USE_IMIN_PLUG)
   #undef I_MIN_PIN
   #define I_MIN_PIN          -1
@@ -1343,6 +1352,9 @@
   #undef I_MAX_PIN
   #define I_MAX_PIN          -1
 #endif
+#if NONE(USE_IMIN_PLUG, USE_IMAX_PLUG)
+  #undef I_STOP_PIN
+#endif
 #if DISABLED(USE_JMIN_PLUG)
   #undef J_MIN_PIN
   #define J_MIN_PIN          -1
@@ -1351,6 +1363,9 @@
   #undef J_MAX_PIN
   #define J_MAX_PIN          -1
 #endif
+#if NONE(USE_JMIN_PLUG, USE_JMAX_PLUG)
+  #undef J_STOP_PIN
+#endif
 #if DISABLED(USE_KMIN_PLUG)
   #undef K_MIN_PIN
   #define K_MIN_PIN          -1
@@ -1359,6 +1374,9 @@
   #undef K_MAX_PIN
   #define K_MAX_PIN          -1
 #endif
+#if NONE(USE_KMIN_PLUG, USE_KMAX_PLUG)
+  #undef K_STOP_PIN
+#endif
 
 #if DISABLED(X_DUAL_ENDSTOPS) || X_HOME_TO_MAX
   #undef X2_MIN_PIN
diff --git a/buildroot/tests/FYSETC_F6 b/buildroot/tests/FYSETC_F6
index 9306686af5..17f8eb42b1 100755
--- a/buildroot/tests/FYSETC_F6
+++ b/buildroot/tests/FYSETC_F6
@@ -10,7 +10,7 @@ set -e
 # Build with the default configurations
 #
 restore_configs
-opt_set MOTHERBOARD BOARD_FYSETC_F6_13
+opt_set MOTHERBOARD BOARD_FYSETC_F6_13 LCD_SERIAL_PORT 1
 opt_enable DGUS_LCD_UI_FYSETC
 exec_test $1 $2 "FYSETC F6 1.3 with DGUS" "$3"