MarlinFirmware · chepo92 · Dec 15, 2025 · Dec 15, 2025 · Dec 15, 2025 · Dec 15, 2025
diff --git a/Marlin/Configuration.h b/Marlin/Configuration.h
@@ -923,6 +923,7 @@
 
   //#define PID_EDIT_MENU         // Add PID editing to the "Advanced Settings" menu. (~700 bytes of flash)
   //#define PID_AUTOTUNE_MENU     // Add PID auto-tuning to the "Advanced Settings" menu. (~250 bytes of flash)
+  //#define DISABLE_M303_AUTOTUNE // Disable the M303 PID autotune command to save ~2.7K bytes of flash.
 #endif
 
 // @section safety

diff --git a/Marlin/src/gcode/gcode.cpp b/Marlin/src/gcode/gcode.cpp
@@ -832,7 +832,7 @@ void GcodeSuite::process_parsed_command(bool no_ok/*=false*/) {
         case 302: M302(); break;                                  // M302: Allow cold extrudes (set the minimum extrude temperature)
       #endif
 
-      #if HAS_PID_HEATING
+      #if HAS_PID_AUTOTUNE
         case 303: M303(); break;                                  // M303: PID autotune
       #endif
 

diff --git a/Marlin/src/gcode/gcode.h b/Marlin/src/gcode/gcode.h
@@ -1014,7 +1014,7 @@ class GcodeSuite {
     static void M302();
   #endif
 
-  #if HAS_PID_HEATING
+  #if HAS_PID_AUTOTUNE
     static void M303();
   #endif
 

diff --git a/Marlin/src/gcode/temp/M303.cpp b/Marlin/src/gcode/temp/M303.cpp
@@ -22,7 +22,7 @@
 
 #include "../../inc/MarlinConfig.h"
 
-#if HAS_PID_HEATING
+#if HAS_PID_AUTOTUNE
 
 #include "../gcode.h"
 #include "../queue.h" // for flush_tx
@@ -85,4 +85,4 @@ void GcodeSuite::M303() {
   queue.flush_rx();
 }
 
-#endif // HAS_PID_HEATING
+#endif // HAS_PID_AUTOTUNE
diff --git a/Marlin/src/inc/Conditionals-5-post.h b/Marlin/src/inc/Conditionals-5-post.h
@@ -2731,6 +2731,11 @@
   #define HAS_PID_HEATING 1
 #endif
 
+// PID autotune (M303 command)
+#if HAS_PID_HEATING && DISABLED(DISABLE_M303_AUTOTUNE)
+  #define HAS_PID_AUTOTUNE 1
+#endif
+
 // Thermal protection
 #if ENABLED(THERMAL_PROTECTION_HOTENDS) && WATCH_TEMP_PERIOD > 0
   #define WATCH_HOTENDS 1

diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
@@ -1051,6 +1051,12 @@ static_assert(NUM_SERVOS <= NUM_SERVO_PLUGS, "NUM_SERVOS (or some servo index) i
   #endif
 #endif
 
+
+/* PID autotune (M303 command) */
+#if ALL(PID_AUTOTUNE_MENU, DISABLE_M303_AUTOTUNE)
+  #error "Can't enable PID_AUTOTUNE_MENU and DISABLE_M303_AUTOTUNE at the same time."
+#endif
+
 /**
  * Bed Heating Options - PID vs Limit Switching
  */

diff --git a/Marlin/src/lcd/dwin/proui/dwin.cpp b/Marlin/src/lcd/dwin/proui/dwin.cpp
@@ -1695,21 +1695,23 @@ void dwinLevelingDone() {
 
 #if HAS_PID_HEATING
 
-  void dwinStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-    hmiData.pidCycles = count;
-    switch (hid) {
-      #if ENABLED(PIDTEMP)
-        case 0 ... HOTENDS - 1: hmiData.hotendPIDT = temp; break;
-      #endif
-      #if ENABLED(PIDTEMPBED)
-        case H_BED: hmiData.bedPIDT = temp; break;
-      #endif
-      #if ENABLED(PIDTEMPCHAMBER)
-        case H_CHAMBER: hmiData.chamberPIDT = temp; break;
-      #endif
-      default: break;
+  #if HAS_PID_AUTOTUNE
+    void dwinStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+      hmiData.pidCycles = count;
+      switch (hid) {
+        #if ENABLED(PIDTEMP)
+          case 0 ... HOTENDS - 1: hmiData.hotendPIDT = temp; break;
+        #endif
+        #if ENABLED(PIDTEMPBED)
+          case H_BED: hmiData.bedPIDT = temp; break;
+        #endif
+        #if ENABLED(PIDTEMPCHAMBER)
+          case H_CHAMBER: hmiData.chamberPIDT = temp; break;
+        #endif
+        default: break;
+      }
     }
-  }
+  #endif
 
   void dwinPIDTuning(tempcontrol_t result) {
     hmiValue.tempControl = result;

diff --git a/Marlin/src/lcd/dwin/proui/dwin.h b/Marlin/src/lcd/dwin/proui/dwin.h
@@ -398,7 +398,9 @@ void drawMaxAccelMenu();
 // PID
 #if HAS_PID_HEATING
   #include "../../../module/temperature.h"
-  void dwinStartM303(const int count, const heater_id_t hid, const celsius_t temp);
+  #if HAS_PID_AUTOTUNE
+    void dwinStartM303(const int count, const heater_id_t hid, const celsius_t temp);
+  #endif
   void dwinPIDTuning(tempcontrol_t result);
   #if ANY(PID_AUTOTUNE_MENU, PID_EDIT_MENU)
     #if ENABLED(PIDTEMP)

diff --git a/Marlin/src/lcd/dwin/proui/proui_extui.cpp b/Marlin/src/lcd/dwin/proui/proui_extui.cpp
@@ -213,9 +213,11 @@ namespace ExtUI {
       }
     }
 
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      dwinStartM303(count, hid, temp);
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        dwinStartM303(count, hid, temp);
+      }
+    #endif
 
   #endif
 

diff --git a/Marlin/src/lcd/extui/anycubic_chiron/chiron_extui.cpp b/Marlin/src/lcd/extui/anycubic_chiron/chiron_extui.cpp
@@ -167,9 +167,11 @@ namespace ExtUI {
     void onPIDTuning(const pidresult_t rst) {
       // Called for temperature PID tuning result
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/anycubic_i3mega/anycubic_extui.cpp b/Marlin/src/lcd/extui/anycubic_i3mega/anycubic_extui.cpp
@@ -156,9 +156,11 @@ namespace ExtUI {
     void onPIDTuning(const pidresult_t rst) {
       // Called for temperature PID tuning result
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/anycubic_vyper/vyper_extui.cpp b/Marlin/src/lcd/extui/anycubic_vyper/vyper_extui.cpp
@@ -168,9 +168,11 @@ namespace ExtUI {
     void onPIDTuning(const pidresult_t rst) {
       // Called for temperature PID tuning result
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/dgus/dgus_extui.cpp b/Marlin/src/lcd/extui/dgus/dgus_extui.cpp
@@ -203,9 +203,11 @@ namespace ExtUI {
       }
       screen.gotoScreen(DGUS_SCREEN_MAIN);
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/dgus_e3s1pro/dgus_e3s1pro_extui.cpp b/Marlin/src/lcd/extui/dgus_e3s1pro/dgus_e3s1pro_extui.cpp
@@ -176,9 +176,11 @@ namespace ExtUI {
       // Called for temperature PID tuning result
       screen.pidTuning(rst);
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/dgus_reloaded/dgus_reloaded_extui.cpp b/Marlin/src/lcd/extui/dgus_reloaded/dgus_reloaded_extui.cpp
@@ -172,9 +172,11 @@ namespace ExtUI {
       // Called for temperature PID tuning result
       screen.pidTuning(rst);
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/example/example.cpp b/Marlin/src/lcd/extui/example/example.cpp
@@ -170,9 +170,11 @@ namespace ExtUI {
         case PID_DONE:            break;
       }
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/ftdi_eve_touch_ui/ftdi_eve_extui.cpp b/Marlin/src/lcd/extui/ftdi_eve_touch_ui/ftdi_eve_extui.cpp
@@ -208,9 +208,11 @@ namespace ExtUI {
       }
       GOTO_SCREEN(StatusScreen);
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif // HAS_PID_HEATING
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/ia_creality/ia_creality_extui.cpp b/Marlin/src/lcd/extui/ia_creality/ia_creality_extui.cpp
@@ -419,9 +419,11 @@ void onPostprocessSettings() {}
     #endif
     onStatusChanged(F("PID Tune Finished"));
   }
-  void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-    // Called by M303 to update the UI
-  }
+  #if HAS_PID_AUTOTUNE
+    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+      // Called by M303 to update the UI
+    }
+  #endif
 #endif
 
 #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/malyan/malyan_extui.cpp b/Marlin/src/lcd/extui/malyan/malyan_extui.cpp
@@ -128,9 +128,11 @@ namespace ExtUI {
       }
     }
 
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
 
   #endif
 

diff --git a/Marlin/src/lcd/extui/nextion/nextion_extui.cpp b/Marlin/src/lcd/extui/nextion/nextion_extui.cpp
@@ -155,9 +155,11 @@ namespace ExtUI {
       // Called for temperature PID tuning result
       nextion.panelInfo(37);
     }
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
-      // Called by M303 to update the UI
-    }
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp) {
+        // Called by M303 to update the UI
+      }
+    #endif
   #endif
 
   #if ENABLED(MPC_AUTOTUNE)

diff --git a/Marlin/src/lcd/extui/ui_api.cpp b/Marlin/src/lcd/extui/ui_api.cpp
@@ -935,9 +935,11 @@ namespace ExtUI {
       thermalManager.setPID(uint8_t(tool), p, i, d);
     }
 
-    void startPIDTune(const celsius_t temp, extruder_t tool) {
-      thermalManager.PID_autotune(temp, heater_id_t(tool), 8, true);
-    }
+    #if HAS_PID_AUTOTUNE
+      void startPIDTune(const celsius_t temp, extruder_t tool) {
+        thermalManager.PID_autotune(temp, heater_id_t(tool), 8, true);
+      }
+    #endif
   #endif
 
   #if ENABLED(PIDTEMPBED)
@@ -949,9 +951,11 @@ namespace ExtUI {
       thermalManager.temp_bed.pid.set(p, i, d);
     }
 
-    void startBedPIDTune(const celsius_t temp) {
-      thermalManager.PID_autotune(temp, H_BED, 4, true);
-    }
+    #if HAS_PID_AUTOTUNE
+      void startBedPIDTune(const celsius_t temp) {
+        thermalManager.PID_autotune(temp, H_BED, 4, true);
+      }
+    #endif
   #endif
 
   void injectCommands_P(PGM_P const gcode) { queue.inject_P(gcode); }

diff --git a/Marlin/src/lcd/extui/ui_api.h b/Marlin/src/lcd/extui/ui_api.h
@@ -567,7 +567,9 @@ namespace ExtUI {
   #endif
   #if HAS_PID_HEATING
     void onPIDTuning(const pidresult_t rst);
-    void onStartM303(const int count, const heater_id_t hid, const celsius_t temp);
+    #if HAS_PID_AUTOTUNE
+      void onStartM303(const int count, const heater_id_t hid, const celsius_t temp);
+    #endif
   #endif
   #if ENABLED(MPC_AUTOTUNE)
     void onMPCTuning(const mpcresult_t rst);

diff --git a/Marlin/src/module/temperature.cpp b/Marlin/src/module/temperature.cpp
@@ -772,7 +772,7 @@ void Temperature::factory_reset() {
 
 } // factory_reset
 
-#if HAS_PID_HEATING
+#if HAS_PID_AUTOTUNE
 
   inline void say_default_() { SERIAL_ECHOPGM("#define DEFAULT_"); }
 
@@ -1031,7 +1031,7 @@ void Temperature::factory_reset() {
       return;
   }
 
-#endif // HAS_PID_HEATING
+#endif // HAS_PID_AUTOTUNE
 
 #if ENABLED(MPC_AUTOTUNE)
 

diff --git a/Marlin/src/module/temperature.h b/Marlin/src/module/temperature.h
@@ -1257,16 +1257,18 @@ class Temperature {
 
     static bool tuning_idle(const millis_t &ms);
 
-    /**
-     * M303 PID auto-tuning for hotends or bed
-     */
     #if HAS_PID_HEATING
 
       #if HAS_PID_DEBUG
         static bool pid_debug_flag;
       #endif
 
-      static void PID_autotune(const celsius_t target, const heater_id_t heater_id, const int8_t ncycles, const bool set_result=false);
+      /**
+       * M303 PID auto-tuning for hotends or bed
+       */
+      #if HAS_PID_AUTOTUNE
+        static void PID_autotune(const celsius_t target, const heater_id_t heater_id, const int8_t ncycles, const bool set_result=false);
+      #endif // HAS_PID_AUTOTUNE
 
       // Update the temp manager when PID values change
       #if ENABLED(PIDTEMP)