All codesService call
SC546
Unstable fusing temperature
BFusing
Level B — stop, power-cycle may clear
First check
Clean thermistor, check fusing fan, then fuser.
What it means
Temperature hunting after ready. Dirty thermistor, failing lamp, or airflow.
Likely causes
- Glazed thermistor
- Fusing fan
- Heater aging
- Wrong paper/temp SP
On-site steps
Parts to have on the truck
- Thermistor
- Fusing fan
- Fusing unit
Confirm the subcode and part number in the FSM for this serial. Raicoh is a field companion, not a replacement for the book.