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DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P251B

P251BPTO Enable Switch Circuit Low

P251B indicates that the powertrain control module (PCM) has detected a low-voltage condition on the power take-off (PTO) enable switch circuit, which is used to engage auxiliary equipment driven by the engine. The PCM expects to see a specific voltage on the switch signal circuit when the switch is in the off or on position, and a low reading tells the module that the circuit is shorted to ground or the switch is stuck closed.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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