HMS_0C00_0001
Bambu Lab 3D Printer
Severity: ModerateWhat Does This Error Mean?
HMS_0C00_0001 on a Bambu Lab printer means the hotend heatbreak fan has stalled. This fan keeps the upper hotend cool to prevent heat creep. Power off, clean the fan blades, and check it spins freely. A failed fan needs replacement to prevent jams.
Affected Models
- Bambu Lab X1 Carbon
- Bambu Lab X1
- Bambu Lab P1S
- Bambu Lab P1P
- Bambu Lab A1
Common Causes
- Dust or filament debris jamming the fan blades
- Fan bearing worn (typical after 1,000+ print hours)
- Fan cable loose at the toolhead connector
- Damaged fan blade from a print obstruction
How to Fix It
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Power off and let the hotend cool.
Switch the printer off and wait 10 minutes for the hotend to cool to a touchable temperature.
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Open the toolhead cover.
Remove the Phillips screw on the toolhead front cover and lift it off. The heatbreak fan is the small fan mounted directly on the hotend heatsink fins.
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Clean the fan.
Use compressed air or a soft brush to clear dust from the blades and the heatsink fins behind. Spin the fan by hand — it should rotate freely without grinding.
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Check the fan cable.
The fan has a small 2-pin connector. Confirm it is firmly plugged in. Reconnect if loose.
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Replace the fan if it does not spin.
If the fan does not spin under power, or grinds when rotated by hand, replace it. Bambu Lab sells the heatbreak fan as a service part for roughly USD 8–15. Replacement is a 5-minute job.
Frequently Asked Questions
What does the heatbreak fan do?
The heatbreak fan cools the upper section of the hotend (above the heat block) to prevent filament from softening too high in the heatbreak. Without active cooling, soft filament jams the heatbreak — known as 'heat creep'.
Will my Bambu Lab print badly if I ignore HMS_0C00_0001?
Yes — without the heatbreak fan, filament softens above the heat block and jams. You will see under-extrusion, then a complete clog. The print fails. Bambu Lab refuses to print until the fan is verified to prevent this.