HMS 0300 0300
Bambu Lab 3D Printer
Severity: CriticalWhat it means
HMS 0300 0300 means the nozzle heater is not reaching the target temperature within the expected time.
The heater cartridge may be failing, or there is a connection issue.
Check the hotend assembly and heater connection.
Affected Models
- Bambu Lab X1 Carbon
- Bambu Lab X1
- Bambu Lab P1S
- Bambu Lab P1P
- Bambu Lab A1
Common Causes
- Heater cartridge failing or burned out
- Hotend not fully seated — heater not making contact
- Excessive cooling from part cooling fan hitting the hotend
- Printing in a very cold environment
- Power delivery issue to the heater
How to Fix It
-
Re-seat the hotend assembly.
Remove and reinstall the hotend, making sure it clicks fully into place.
-
Check if the hotend heats at all.
Start a preheat.
If the temperature does not rise at all, the heater is dead.
If it rises slowly, there may be a poor connection. -
Try a different hotend assembly if available.
Bambu Lab hotends are modular.
Swapping in a known good one confirms whether the old one is faulty. -
Contact Bambu Lab support for a replacement hotend.
If the hotend is within warranty, Bambu Lab will replace it.
Frequently Asked Questions
How long does a Bambu Lab hotend last?
The hotend assembly typically lasts thousands of hours.
The nozzle itself (hardened steel on X1C) lasts much longer than brass nozzles on other printers.
Can I replace just the heater cartridge?
On Bambu Lab printers, the hotend is an integrated assembly.
It is easier and safer to replace the entire hotend unit rather than individual components.