SC556

What it means

Fusing temperature control error. Confirm the exact subcode against the FSM for this serial — meaning can shift by generation.

Likely causes

• Control loop failed. History will show 541–547 next to it. Fix that, then reset.

1. 1Read historySP5-990. Note the subcode and anything logged in the same minute. The standing number is often the last, not the first.
2. 2I/O then FRUSP5-803 / 5-804 on the related sensor or motor. Likely FRU: Fusing unit, PSU.

Parts to have on the truck

• Fusing unit
• PSU

Related codes