- 3D printers
- 3D printer
0300-0400-0002-0001
Bambu Lab 0300-0400-0002-0001 on a 3D printer: part cooling fan
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Bambu Lab HMS 0300-0400-0002-0001 means the part cooling fan is spinning slower than expected or has stopped. Switch it off, check whether anything blocks the blades and check its connector before asking for a replacement.
Safety first
Stop and check this first
- Do not disable or bypass the thermal protection or change the firmware to clear the alert: it is what cuts the heat when the temperature does not add up. Do not open the printer's power supply or mains board: anything at mains voltage is for the service team.
- Bambu Lab asks for the fan to be off before cleaning it, because it can start unexpectedly and injure you, and to wait for the hotend to cool if the printer was just used.
Safe checks you can perform
- Fan off and blades free
- Fan connector
- Test from the fans menu
Leave these tasks to a qualified professional
- Do not attempt this professional task: Front housing assembly with fan
- Do not attempt this professional task: Fan replacement on the H2 series
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Front housing assembly with fan
What they doOn X1 and P1, the fan is built into the front housing assembly, which is replaced as a whole following Bambu Lab's guide.
They must show youthe Control, Fans test after the swap.
In writingthe reference of the assembly fitted.
Fan replacement on the H2 series
What they doOn H2D, H2D Pro and H2S only the fan is replaced, using each model's official guide.
They must show youthat the error does not come back.
In writingthe part replaced and the test result.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Fan off and blades free
- Who:
- you.
- How:
- turn the fan off from the printer controls, rotate the blades by hand to feel for resistance and remove filament strings, dust or objects.
- Result that matters:
- whether the blades turn freely.
- If there was debris:
- remove it and turn the fan back on.
- If they turn freely:
- move on to the connector.
- Evidence to keep:
- photo of what you removed.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
Fan connector
- Who:
- you, on X1, P1 and P2; on H2 follow your model's disassembly guide.
- How:
- with the printer off, remove the front housing (magnetic on X1, P1 and P2), disconnect and firmly reconnect the connector, pulling it straight out from the board.
- Result that matters:
- all pins are properly seated.
- If the error goes away:
- it was the connector.
- If it stays:
- the fan motor is next.
- Evidence to keep:
- photo of the connector in place.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
Test from the fans menu
- Who:
- you.
- How:
- power the printer on and go to Control, Fans, Part Cooling Fan to test the fan, as Bambu Lab says.
- Result that matters:
- it spins smoothly, with no noise or vibration and without the error returning.
- If it works well:
- the problem is solved.
- If it does not spin or is noisy:
- a replacement is needed.
- Evidence to keep:
- short video of the test.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- 3D printers
- Brand
- Bambu Lab
- Product type
- 3D printer
Known code variants
- 0300 0400 0002 0001
- Bambu Lab part cooling fan
- Bambu Lab ventilador de capa
- HMS_0300-0400-0002-0001
What it means
Bambu Lab explains that the printer monitors the part cooling fan's speed feedback and raises this error when it is slower than its design specification. It applies to the X1, P (P1 and P2) and H2 series. The causes it gives are blades blocked by bits of filament, dust or other debris in the toolhead or duct, a loose connector giving irregular power and, if there is neither a blockage nor a bad connection, a defective or worn fan motor.
Warnings and stop conditions
- Criticaleditorial warning
Do not disable or bypass the thermal protection or change the firmware to clear the alert: it is what cuts the heat when the temperature does not add up. Do not open the printer's power supply or mains board: anything at mains voltage is for the service team.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
- Mediumsource verified
Bambu Lab asks for the fan to be off before cleaning it, because it can start unexpectedly and injure you, and to wait for the hotend to cool if the printer was just used.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
Symptoms and causes
Probable causes · in order
- Blades blocked by debrisCommon
Bits of filament, dust or other debris building up in the toolhead or the duct can stop the fan blades turning.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
- Loose connectorPossible
If the fan cable works loose or slightly out of the board, power arrives poorly or only some of the time.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
- Faulty fan motorPossible
If there is no blockage and no bad connection, Bambu Lab says the fan motor itself may be defective or worn out.
Evidence: Bambu Lab Wiki: HMS_0300-0400-0002-0001: The Part Cooling Fan speed is too slow or stopped. It may be stuck, or the connector may not be plugged in properly.
Virtual technician
Does 0300-0400-0002-0001 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Bambu Lab Wiki: HMS Home Page, List of Error Codes for Bambu Lab 3D Printers
Bambu Lab · 2026 · official_doc
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