All codes
Service call
SC121
Scanner home position error 2
BScanner / optics
Level B — stop, power-cycle may clear
First check
HP sensor stuck on, or flag bent so it never clears the sensor.
What it means
Second-stage HP error — sensor never de-asserted after the carriage left home.
Likely causes
- HP sensor stuck high
- Bent HP flag
- Scanner motor not actually moving
On-site steps
Parts to have on the truck
- HP sensor
- Scanner motor
Related codes
Confirm the subcode and part number in the FSM for this serial. Raicoh is a field companion, not a replacement for the book.