SPN 51
CAUTION
Throttle position
The truck's control module (ECU) reports a fault on: Throttle position.
SPN 51 means a truck control module (ECU) flagged a fault on throttle position, part of the Engine system on heavy-duty diesel trucks. DERATE rates it CAUTION: you can keep driving carefully, but get it checked soon. Part usually replaced: Throttle position sensor, $80–$350 (aftermarket to dealer) plus 0.5–1.5 h labor.
Engine
Can I keep driving?
Yes, carefully. It does not usually cut power, but get it checked soon.
Part usually replaced
Throttle position sensor
$80–$350 (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.