Powertrain, generic (extended)

P251E PTO Engine Shutdown Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P251E reports that the PTO engine shutdown input reads too low. Whether low means stop now or all clear depends on the maker's wiring, so the practical effect varies: the module may treat the line as an active stop request and refuse to keep the engine running in PTO mode, or it may simply flag the line as shorted and ignore it. Typical causes are a chafed wire grounded on the frame, a corroded connector at the body interface or a stop switch shorted to ground. No manufacturer publishes P251E with a threshold or MIL rule; CARB defines the PTO unit, and GM's PTO bulletin PIP6108 for P251A shows that ground quality plays a big part in these body-builder circuits. Sibling codes: P251D for an open line, P251F for a high reading.

Likely causes

Shutdown wire chafed through to chassis ground
Corroded connector at the body builder interface
Equipment stop switch shorted to ground

Symptoms

  • Engine stops or will not stay running while PTO is used
  • PTO function disabled

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

P251DP251FP251B

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