OBD-II code · Powertrain (generic, extended)
P251B PTO Enable Switch Circuit Low
The PTO enable switch input reads stuck low — typically a short to ground or a permanently closed switch. The ECM either sees PTO enabled when the operator has not requested it, or cannot release the PTO mode after work.
Is it safe to drive with P251B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySwitch wire shorted to ground
- PossibleSwitch stuck closed
- Less likelyConnector pins corroded - high contact resistance
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Pto Enable Switch, Wiring Harness
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.