OBD-II code · Powertrain (generic, extended)
P25B7 Auxiliary Ignition Switch On/Start Position Circuit
General electrical fault on the auxiliary ignition switch On/Start input. Used on commercial vehicles or upfit applications where a second ignition switch (in a sleeper cab, work platform or crew compartment) can crank the engine.
Is it safe to drive with P25B7?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen or shorted wire
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Auxiliary Ignition Switch, Wiring Harness
Related codes
- P25B4Turbocharger/Supercharger Wastegate A Stuck Closed
- P25B5Turbocharger/Supercharger Wastegate B Stuck Open
- P25B6Turbocharger/Supercharger Wastegate B Stuck Closed
- P25B8Auxiliary Ignition Switch On/Start Position Circuit Low
- P25B9Auxiliary Ignition Switch On/Start Position Circuit High
- P25BARegeneration Control Switch Circuit/Open
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.