HMS 0300-1d00-0001-0001: extruder position sensor fault
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The extruder reports its own movement back to the controller, and that feedback has become unreliable. Check the toolhead cable seating and clear filament dust from the extruder before assuming the sensor has failed.
A closed-loop extruder does not just command the motor and hope. It measures what actually happened and compares the two. That is what lets the machine detect a jam or a runout without a separate switch, and it is why the printer stops when the feedback path goes quiet rather than carrying on blind.
Affected machines: A2L, H2, H2S, P2S, X1 series, X2D.
Dust and swarf reach the sensor before the sensor wears out
The extruder is the dustiest place on the printer. The drive gears shave a fine powder off every spool, and that powder collects exactly where the mechanism is measured. A sensor reading that drifts or drops out intermittently is far more often a contamination problem than a component failure, and it costs nothing to check first.
Code appears during or shortly after filament movement, sometimes intermittently across several prints
Contamination in the extruder assembly, or a loose toolhead cable carrying the feedback signal
- Power off and open the extruder assembly according to your machine documentation.
- Brush out accumulated filament dust, paying attention to the area around the drive gears.
- Reseat the toolhead cable at both ends. An intermittent fault that follows toolhead position points at this cable.
- Check that the firmware is current, since feedback thresholds are tuned in firmware and have been revised.
Do not defeat this check to finish a print. The same feedback path is what stops the extruder grinding through filament when the hotend is blocked, so running without it turns a recoverable jam into a stripped filament and a dismantled toolhead.
If it only appears with one spool
Feedback faults that follow a particular filament are usually the filament, not the printer. Soft or badly wound material deforms under the drive gear instead of advancing cleanly, and the measured movement stops matching the commanded movement. Try a known good spool before ordering parts.
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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