HMS 0300-9100-0001-0008: chamber heater control abnormal, vent blocked
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HMS 0300-9100-0001-0008 means the chamber heater control has gone abnormal, and Bambu names the likely reason: the left chamber heater vent is blocked, so the heater cooked itself and its over-temperature protection cut in. That protection working is the good news. The blockage is what you have to find.
Affected machines: H2D, X1 series and X2D. A heated chamber works by pushing warm air through the enclosure, and it depends on that air actually moving. Restrict the outlet and the heater element sees its own heat instead of the chamber, so the temperature at the element runs away while the chamber stays cold.
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What blocks a chamber vent
Three things, in order of how often we see them. A print or a piece of purge waste that has fallen into the path and is sitting against the grille. A filter that has never been changed and is now a felt mat. And dust bound together with filament residue, which forms a surprisingly solid crust in a warm machine.
Look with a torch rather than by feel. The vent is easy to declare clear from a glance and still be half obstructed by something dark against a dark plastic housing.
Chamber will not reach temperature, or the printer stops with a chamber heater control fault
Blocked heater vent tripping over-temperature protection, occasionally a bad chamber sensor
- Power off at the wall and let the chamber cool fully. The heater area stays hot long after a print stops.
- Open the machine and inspect the left chamber heater vent with a torch, looking for debris against the grille.
- Remove anything sitting in the path, including purge waste that has fallen behind the plate.
- Check and clean or replace the chamber filter if the model has one in that path.
- Power up and start a chamber preheat, watching whether the temperature rises steadily rather than stalling.
- If the vent is clear and the fault returns, measure the chamber sensor: around 100k ohm cold is healthy. A wrong reading makes the controller behave as though the chamber is cold and overdrive the heater.
Do not defeat the protection by clearing the code and running again. An over-temperature cutout on a heater inside an enclosure exists for one reason, and repeatedly resetting it is how a warning becomes a fire.
The sensor-side fault on the same system is chamber sensor open circuit. Our page on enclosed printers explains what chamber heat is for, ABS and ASA covers the materials that need it, and the troubleshooting index covers the rest.
HMS 0300-9100-0001-0008 FAQ
Can I print PLA while this is unresolved?
Yes. PLA does not use chamber heating, and the printer will run without it.
Where exactly is the left vent?
On the left side of the chamber heater assembly. Consult the model page for your machine, because it moved between the X1 and the H2D.
Does the filter cause this?
A loaded filter can. It is part of the same air path, and it is the cheapest thing to rule out.
What should the chamber sensor read?
Around 100k ohm at room temperature. Well away from that and the controller is working on bad information.
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