HMS 0300-9300-0001-0006: chamber temperature sensor fault
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The sensor that reports chamber air temperature is not returning a believable value. Prints in PLA are usually unaffected, but chamber controlled materials such as ABS and ASA lose the regulation they depend on, so warping returns.
On machines with a heated or actively managed chamber, a separate sensor measures the air rather than the bed or nozzle. It is what lets the printer hold an enclosure at a stable temperature for high-shrinkage materials. When that reading fails, chamber regulation is what you lose.
Affected machines: H2, P2S, X1 series, X2D.
Why this matters for ABS and ASA but not PLA
High shrinkage materials warp because the lower layers cool and contract while the upper ones are still being laid down. A managed chamber slows that gradient. Take the measurement away and the printer can no longer hold the chamber where the material needs it, so parts that printed cleanly last week start lifting at the corners. PLA does not need the regulation, which is why the same fault can go unnoticed for weeks.
Code appears at power-on or during chamber heating, and warping on ABS or ASA returns with it
Disconnected or damaged chamber sensor, or a broken lead in the enclosure loom
- Power off at the wall and let the chamber cool.
- Locate the chamber sensor and reseat its connector at both ends.
- Measure the sensor cold. A 100k NTC should read near 100k ohm at room temperature.
- Inspect the lead where it passes through the enclosure wall, which is where it chafes.
Do not run high temperature materials with chamber regulation disabled and the door shut in order to work around this. Without a valid chamber reading the printer cannot manage enclosure temperature, and the electronics bay on these machines is not rated for an uncontrolled hot chamber.
Rule out the sensor before blaming the material
If ABS or ASA has suddenly started warping on a machine that used to handle it, check for this code before you change filament brand or re-dry the spool. A silent loss of chamber regulation looks exactly like a material problem, and people replace a lot of filament chasing it.
Wrong code? The full Bambu HMS code index lists all 588 codes with the subsystem each one points to and which printers show it.
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