P25A8Fuel Mode Select Switch Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P25A8 records a fuel mode select switch signal that jumps or drops out briefly instead of staying in a stable state. The module sees transitions it cannot attribute to a real press, often while driving over rough roads, which points to a loose terminal, a cracked solder joint in the switch or a harness rubbing behind the trim. Because a press on GM's bi-fuel systems toggles the fuel even while driving, as GM states for its 2015 Impala, unwanted pulses could trigger needless fuel changes, which is why such glitches are flagged. No manufacturer documents P25A8 publicly. Wiggle tests with live data, checking terminal tension and inspecting any conversion harness are the right sequence. Short dropouts may come and go, and the code may return after clearing.
- What you may notice
- Occasional unexpected fuel mode changes
- Switch light flickers
- Code returns sporadically after clearing
- Likely causes
- LikelyLoose terminal or poor contact at the switch connector
- PossibleCracked solder joint inside the switch
- PossibleHarness rubbing behind the trim and shorting briefly
- 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.