Powertrain, generic (extended)

P251F PTO Engine Shutdown Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P251F is the high-side fault of the PTO engine shutdown input: the voltage stays near supply level where the module expects a defined switching state. A shutdown wire touching a powered circuit in the body harness, a missing ground on the equipment controller, or an add-on module that drives the line permanently are typical. The main risk is that a real stop request from the body equipment is no longer recognised, or that the module locks out PTO operation as a precaution. Public maker documentation for P251F was not found; CARB covers PTO units in its OBD rules, and GM's PIP6108 on P251A illustrates how ground faults distort PTO-related inputs on medium-duty trucks. P251D is the open-circuit and P251E the low-level variant.

Likely causes

Shutdown wire shorted to a powered circuit in the body harness
Body equipment controller without ground
Retrofitted control module holding the line high

Symptoms

  • Engine does not stop when equipment shutdown is triggered
  • PTO operation blocked

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–400
Time0.5–3 h

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

Parts involved

pto shutdown circuit

Related codes

P251DP251EP251C

References: law.cornell.edu, static.nhtsa.gov.