🐛 Fix Bed/Chamber PID Autotune with MPCTEMP (#23983)

Marlin/src/gcode/temp/M303.cpp

@@ -71,6 +71,7 @@ void GcodeSuite::M303() {
       case H_CHAMBER: default_temp = PREHEAT_1_TEMP_CHAMBER; break;
     #endif
     default:
+      SERIAL_ECHOPGM(STR_PID_AUTOTUNE);
       SERIAL_ECHOLNPGM(STR_PID_BAD_HEATER_ID);
       TERN_(EXTENSIBLE_UI, ExtUI::onPidTuning(ExtUI::result_t::PID_BAD_EXTRUDER_NUM));
       TERN_(DWIN_LCD_PROUI, DWIN_PidTuning(PID_BAD_EXTRUDER_NUM));