Powertrain, generic (extended)

P251D PTO Engine Shutdown Circuit/Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P251D covers the engine shutdown line of a power take-off installation. On trucks with body equipment such as cranes, pumps or aerial devices, a hard-wired signal lets the PTO controller or an equipment stop button tell the engine module to switch the engine off. P251D means the module cannot read a valid state on that line, usually because the wire or plug is open. No manufacturer documents P251D publicly or states how the engine reacts; the description rests on CARB's PTO definition and on GM's PTO bulletin PIP6108, which shows how ground and harness faults upset PTO circuits. Depending on calibration the PTO may be locked out, or a stop request from the equipment may no longer reach the engine. P251E and P251F name a fixed low or high level.

Likely causes

Open shutdown wire or loose connector at the body interface
Fault in the body equipment's stop switch or controller output
Shutdown input enabled in calibration but not wired by the upfitter

Symptoms

  • PTO locked out or equipment will not run
  • Equipment stop button no longer shuts down the engine

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 circuitwiring harness

Related codes

P251EP251FP251AP253A

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