An A1 HMS alert includes a complete code and a plain-language message. Record both before restarting. Codes that look similar can point to different sensors or subsystems.
Open the alert in Bambu Handy or on the printer and follow its link to the matching Bambu Wiki page. Begin with reversible checks: remove debris, confirm a connector or accessory that the owner is instructed to inspect, and retry the named calibration once.
Do not treat every HMS message as a reason to factory-reset the printer. A reset erases context without repairing a loose cable, blocked fan or failed heater. Export logs when Bambu support asks for them.
Stop printing for temperature, smoke, damaged mains cable or repeated heater errors. Do not open the power supply or bypass a sensor. This index is a route to the exact manufacturer procedure, not a substitute for the full code.
Many HMS alerts trace back to routine wear rather than a hidden fault, so the A1 maintenance schedule is a good place to start if problems keep recurring. When the message points specifically to the hotend or nozzle, the hotend replacement guide covers the safe swap procedure rather than repeated resets. The HMS code format is shared across Bambu Lab’s line, and works the same way on the dual-nozzle X2D and the newer A2L. Note this is the base A1, a different, larger printer than the Bambu Lab A1 mini, which has its own separate HMS error index on this site.