diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
index 9ced6e4e42..a2fdc9856e 100644
--- a/Marlin/src/inc/SanityCheck.h
+++ b/Marlin/src/inc/SanityCheck.h
@@ -2002,7 +2002,7 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
   #endif
 
   #if REDUNDANT_TEMP_MATCH(SOURCE, E0) && HAS_HOTEND
-    #error "TEMP_SENSOR_REDUNDANT_SOURCE can't be 0 if a hotend is used. E0 always uses TEMP_SENSOR_0."
+    #error "TEMP_SENSOR_REDUNDANT_SOURCE can't be E0 if a hotend is used. E0 always uses TEMP_SENSOR_0."
   #elif REDUNDANT_TEMP_MATCH(SOURCE, COOLER) && HAS_TEMP_COOLER
     #error "TEMP_SENSOR_REDUNDANT_SOURCE can't be COOLER. TEMP_SENSOR_COOLER is in use."
   #elif REDUNDANT_TEMP_MATCH(SOURCE, PROBE) && HAS_TEMP_PROBE
diff --git a/Marlin/src/module/temperature.cpp b/Marlin/src/module/temperature.cpp
index 1e91511f5a..52d0dfb56e 100644
--- a/Marlin/src/module/temperature.cpp
+++ b/Marlin/src/module/temperature.cpp
@@ -369,7 +369,7 @@ const char str_t_thermal_runaway[] PROGMEM = STR_T_THERMAL_RUNAWAY,
       }
     #endif
 
-    TERN_(SINGLENOZZLE, fan = 0); // Always use fan index 0 with SINGLENOZZLE
+    TERN_(SINGLENOZZLE, if (fan < EXTRUDERS) fan = 0); // Always fan 0 for SINGLENOZZLE E fan
 
     if (fan >= FAN_COUNT) return;
 
@@ -1481,7 +1481,7 @@ void Temperature::manage_heater() {
             fan_chamber_pwm = CHAMBER_FAN_BASE + _MAX((CHAMBER_FAN_FACTOR) * (temp_chamber.celsius - temp_chamber.target), 0);
           #endif
           NOMORE(fan_chamber_pwm, 225);
-          set_fan_speed(2, fan_chamber_pwm); // TODO: instead of fan 2, set to chamber fan
+          set_fan_speed(CHAMBER_FAN_INDEX, fan_chamber_pwm); // TODO: instead of fan 2, set to chamber fan
         #endif
 
         #if ENABLED(CHAMBER_VENT)
@@ -1512,7 +1512,7 @@ void Temperature::manage_heater() {
       else if (!flag_chamber_off) {
         #if ENABLED(CHAMBER_FAN)
           flag_chamber_off = true;
-          set_fan_speed(2, 0);
+          set_fan_speed(CHAMBER_FAN_INDEX, 0);
         #endif
         #if ENABLED(CHAMBER_VENT)
           flag_chamber_excess_heat = false;