P25A7Fuel Mode Select Switch Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P25A7 reports a fuel mode select switch signal above the accepted window. With a pull-up input this mostly means the switch never closes its path – an open signal or return wire, a connector half off, a broken switch – or that the line has contact with a supply voltage, for example where an alternative-fuel conversion tapped into nearby wiring. No manufacturer documents P25A7 publicly; it follows CARB's demand that every computer input be checked for out-of-range readings. GM's 2016 Sierra and Silverado bi-fuel supplement shows the switch also carries the fuel indicator light, so a supply fault can affect both. Opposite to P25A6, measuring for voltage on the signal line with the switch unplugged separates a short to power from an open. Selection by switch stops working.
- What you may notice
- Switch has no effect
- Fuel indicator on the switch may stay dark
- Likely causes
- LikelyOpen signal or return wire, connector not seated
- PossibleSignal wire touching a supply voltage, e.g. after aftermarket wiring
- PossibleSwitch contact broken open
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.