Powertrain
generic / SAE
P25B9
Auxiliary Ignition Switch On/Start Position Circuit High
Auxiliary ignition switch On/Start input reads stuck high — short to battery voltage. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / B9
Possible causes
- Wire shorted to battery voltage high
- Connector pins corroded - high contact resistance low
- Supply wire pinched against B+ source low
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 80–500 €
- Estimated time: 0.5–2 h
- Component: auxiliary ignition switch
- Component: wiring harness
- MIL / check engine light
Sources
References
sae:J2012