SPN 91
CAUTION
Accelerator pedal position
The truck's control module (ECU) reports a fault on: Accelerator pedal position.
SPN 91 means a truck control module (ECU) flagged a fault on accelerator pedal position, part of the Engine system on heavy-duty diesel trucks. DERATE rates it CAUTION: drive to a shop today, because the engine may cut power. Part usually replaced: Accelerator pedal assembly, $180–$650 (aftermarket to dealer) plus 0.5–1.5 h labor.
Engine
Can I keep driving?
Drive to a shop today. The engine may cut power (derate) if the fault stays active.
Part usually replaced
Accelerator pedal assembly
$180–$650 (aftermarket to dealer)
Labor: 0.5–1.5 h
USD, part only. Labor is billed at the shop's hourly rate.
Data: DERATE verified base, updated October 2026
Related codes
Read it off your own dash
Take one photo and DERATE tells you whether you can keep driving.
Ask DERATE
DERATE assists. It does not replace inspection by a qualified technician.