diff --git a/Marlin/src/inc/Conditionals_adv.h b/Marlin/src/inc/Conditionals_adv.h
index c9c8fdf2d5..fd7ba59224 100644
--- a/Marlin/src/inc/Conditionals_adv.h
+++ b/Marlin/src/inc/Conditionals_adv.h
@@ -1233,17 +1233,6 @@
   #define CANNOT_EMBED_CONFIGURATION defined(__AVR__)
 #endif
 
-// Fan Kickstart
-#if FAN_KICKSTART_TIME && !defined(FAN_KICKSTART_POWER)
-  #define FAN_KICKSTART_POWER 180
-#endif
-
-#if FAN_MIN_PWM == 0 && FAN_MAX_PWM == 255
-  #define CALC_FAN_SPEED(f) (f ?: FAN_OFF_PWM)
-#else
-  #define CALC_FAN_SPEED(f) (f ? map(f, 1, 255, FAN_MIN_PWM, FAN_MAX_PWM) : FAN_OFF_PWM)
-#endif
-
 // Input shaping
 #if EITHER(INPUT_SHAPING_X, INPUT_SHAPING_Y)
   #define HAS_ZV_SHAPING 1
diff --git a/Marlin/src/inc/Conditionals_post.h b/Marlin/src/inc/Conditionals_post.h
index eaf2d03cea..59b5dab462 100644
--- a/Marlin/src/inc/Conditionals_post.h
+++ b/Marlin/src/inc/Conditionals_post.h
@@ -2719,37 +2719,8 @@
   #define HAS_FAN 1
 #endif
 
-/**
- * Part Cooling fan multipliexer
- */
 #if PIN_EXISTS(FANMUX0)
-  #define HAS_FANMUX 1
-#endif
-
-/**
- * MIN/MAX fan PWM scaling
- */
-#ifndef FAN_OFF_PWM
-  #define FAN_OFF_PWM 0
-#endif
-#ifndef FAN_MIN_PWM
-  #if FAN_OFF_PWM > 0
-    #define FAN_MIN_PWM (FAN_OFF_PWM + 1)
-  #else
-    #define FAN_MIN_PWM 0
-  #endif
-#endif
-#ifndef FAN_MAX_PWM
-  #define FAN_MAX_PWM 255
-#endif
-#if FAN_MIN_PWM < 0 || FAN_MIN_PWM > 255
-  #error "FAN_MIN_PWM must be a value from 0 to 255."
-#elif FAN_MAX_PWM < 0 || FAN_MAX_PWM > 255
-  #error "FAN_MAX_PWM must be a value from 0 to 255."
-#elif FAN_MIN_PWM > FAN_MAX_PWM
-  #error "FAN_MIN_PWM must be less than or equal to FAN_MAX_PWM."
-#elif FAN_OFF_PWM > FAN_MIN_PWM
-  #error "FAN_OFF_PWM must be less than or equal to FAN_MIN_PWM."
+  #define HAS_FANMUX 1  // Part Cooling fan multipliexer
 #endif
 
 /**
@@ -2773,6 +2744,35 @@
   #endif
 #endif
 
+/**
+ * MIN/MAX fan PWM scaling
+ */
+#if EITHER(HAS_FAN, USE_CONTROLLER_FAN)
+  #ifndef FAN_OFF_PWM
+    #define FAN_OFF_PWM 0
+  #endif
+  #ifndef FAN_MIN_PWM
+    #if FAN_OFF_PWM > 0
+      #define FAN_MIN_PWM (FAN_OFF_PWM + 1)
+    #else
+      #define FAN_MIN_PWM 0
+    #endif
+  #endif
+  #ifndef FAN_MAX_PWM
+    #define FAN_MAX_PWM 255
+  #endif
+  #if FAN_MIN_PWM == 0 && FAN_MAX_PWM == 255
+    #define CALC_FAN_SPEED(f) (f ?: FAN_OFF_PWM)
+  #else
+    #define CALC_FAN_SPEED(f) (f ? map(f, 1, 255, FAN_MIN_PWM, FAN_MAX_PWM) : FAN_OFF_PWM)
+  #endif
+#endif
+
+// Fan Kickstart
+#if FAN_KICKSTART_TIME && !defined(FAN_KICKSTART_POWER)
+  #define FAN_KICKSTART_POWER 180
+#endif
+
 // Servos
 #if PIN_EXISTS(SERVO0) && NUM_SERVOS > 0
   #define HAS_SERVO_0 1
diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
index d431415559..034e472e84 100644
--- a/Marlin/src/inc/SanityCheck.h
+++ b/Marlin/src/inc/SanityCheck.h
@@ -1560,11 +1560,11 @@ static_assert(X_MAX_LENGTH >= X_BED_SIZE, "Movement bounds (X_MIN_POS, X_MAX_POS
 /**
  * Part-Cooling Fan Multiplexer requirements
  */
-#if PIN_EXISTS(FANMUX1)
-  #if !HAS_FANMUX
-    #error "FANMUX0_PIN must be set before FANMUX1_PIN can be set."
-  #endif
-#elif PIN_EXISTS(FANMUX2)
+#if HAS_FANMUX && !HAS_FAN0
+  #error "FAN0_PIN must be defined to use Fan Multiplexing."
+#elif PIN_EXISTS(FANMUX1) && !PIN_EXISTS(FANMUX0)
+  #error "FANMUX0_PIN must be set before FANMUX1_PIN can be set."
+#elif PIN_EXISTS(FANMUX2) && !PINS_EXIST(FANMUX0, FANMUX1)
   #error "FANMUX0_PIN and FANMUX1_PIN must be set before FANMUX2_PIN can be set."
 #endif
 
@@ -1608,7 +1608,7 @@ static_assert(X_MAX_LENGTH >= X_BED_SIZE, "Movement bounds (X_MIN_POS, X_MAX_POS
 #endif
 
 #if ENABLED(MPC_INCLUDE_FAN)
-  #if FAN_COUNT < 1
+  #if !HAS_FAN
     #error "MPC_INCLUDE_FAN requires at least one fan."
   #endif
   #if FAN_COUNT < HOTENDS
@@ -1627,8 +1627,8 @@ static_assert(X_MAX_LENGTH >= X_BED_SIZE, "Movement bounds (X_MIN_POS, X_MAX_POS
   #error "To use BED_LIMIT_SWITCHING you must disable PIDTEMPBED."
 #endif
 
-// Fan Kickstart
-#if FAN_KICKSTART_TIME && defined(FAN_KICKSTART_POWER) && !WITHIN(FAN_KICKSTART_POWER, 64, 255)
+// Fan Kickstart power
+#if FAN_KICKSTART_TIME && !WITHIN(FAN_KICKSTART_POWER, 64, 255)
   #error "FAN_KICKSTART_POWER must be an integer from 64 to 255."
 #endif
 
@@ -2454,6 +2454,21 @@ static_assert(X_MAX_LENGTH >= X_BED_SIZE, "Movement bounds (X_MIN_POS, X_MAX_POS
   #endif
 #endif
 
+/**
+ * Make sure FAN_*_PWM values are sensible
+ */
+#if EITHER(HAS_FAN, USE_CONTROLLER_FAN)
+  #if !WITHIN(FAN_MIN_PWM, 0, 255)
+    #error "FAN_MIN_PWM must be a value from 0 to 255."
+  #elif !WITHIN(FAN_MAX_PWM, 0, 255)
+    #error "FAN_MAX_PWM must be a value from 0 to 255."
+  #elif FAN_MIN_PWM > FAN_MAX_PWM
+    #error "FAN_MIN_PWM must be less than or equal to FAN_MAX_PWM."
+  #elif FAN_OFF_PWM > FAN_MIN_PWM
+    #error "FAN_OFF_PWM must be less than or equal to FAN_MIN_PWM."
+  #endif
+#endif
+
 #ifdef REDUNDANT_PART_COOLING_FAN
   #if FAN_COUNT < 2
     #error "REDUNDANT_PART_COOLING_FAN requires a board with at least two PWM fans."