Bambu Lab HMS 0200-0300 — Hotend Overheat Fix Guide

What Does This Error Mean?

HMS 0200-0300 means the hotend has gone hotter than the firmware allows — usually because the cooling fan on the hotend (the small fan that keeps the heatsink cool) failed.
Without that fan, heat creeps up the hotend and the thermistor reads runaway temperature.
Stop the print, let the hotend cool fully, and check the hotend fan.
This is a serious code — keep printing through it and you'll melt the PTFE liner.

Affected Models

Bambu Lab X1
Bambu Lab X1 Carbon
Bambu Lab P1S
Bambu Lab P1P
Bambu Lab A1

Common Causes

Hotend cooling fan stopped or failed
Heatbreak fan wires loose or broken
Hotend fan blocked by debris (filament chunks)
Thermistor reading falsely high (rare)
Heat block PID values corrupted in firmware

How to Fix It

Power off and wait 30 minutes.

After an overheat event, the hotend takes longer than usual to cool because the natural convection isn't enough to dissipate the heat.
30 minutes minimum.
Don't touch the hotend until it's clearly room temperature.
Inspect the hotend cooling fan.

Look at the toolhead — there's a small fan blowing air down across the heatsink (above the heater block).
This is the heatbreak fan, and it must run constantly while the hotend is hot.
Power on the printer and watch — does this fan spin?
If silent, that's your cause.
Check fan blade for blockage.

Sometimes filament debris from a failed print clogs the fan blade.
Look at the heatbreak fan from the front — should you see filament wrapped around the blade or blocking the airflow path?
Pick out anything visible with tweezers (printer powered off).
Test the fan electrical connection.

If the fan blade is clear but the fan still doesn't spin, the wire or the fan itself has failed.
Bambu sells replacement heatbreak fans for around 15 USD.
It's an easy swap once the toolhead is open.
Replace the fan if it's not spinning.

Order the heatbreak fan matching your model.
Replacement videos are in the Bambu wiki.
Don't try to print again until the fan is replaced — running with HMS 0200-0300 melts the PTFE liner inside the heatbreak and that's a much more expensive repair.

Frequently Asked Questions

Can heat creep cause HMS 0200-0300?

Yes — if the heatbreak fan is partially failing (running slowly), heat creeps up from the heater block into the cool zone of the hotend.
Filament softens in the wrong place, jams, and the heater compensates by getting even hotter.
This is exactly what HMS 0200-0300 protects against.

How urgent is HMS 0200-0300?

Don't ignore it.
The PTFE liner in the heatbreak melts above 250°C.
Once melted, the liner narrows and filament jams permanently.
That's a hotend replacement instead of a fan replacement.
Fix the fan now and you save money.