P2551 Torque Management Request Input Signal B High

P2551 is the high-side fault of torque request B: the signal sits above the top of its valid window. Typical electrical causes would be a line touching a battery feed, an interrupted reference ground or a sender that drives its output to full scale. Because an unexpectedly high request could translate into unwanted torque, the engine module discards it and works without channel B. No maker documents P2551 publicly. GM's ECM table 17OBDG04 shows that a vehicle can fill channel B with the brake and traction module's request and validates it with protection value and message counter under P2548, with no separate high code. CARB requires monitoring of such electronic inputs whenever a failure could raise emissions or blind another monitor. P2550 is the low-side fault, P2547 the high fault on input A.

Likely causes

Symptoms

• Check engine light depending on make
• Traction control warning, engine ignores intervention requests

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, gsi.ext.gm.com.