P25C0Alternative Fuel Disable Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P25C0 is set when the alternative fuel disable output reads too low, typically a short to ground somewhere between the engine controller and the gas system. With a high-side driver that pin would then be unable to deliver its voltage; with a low-side driver the line would look permanently switched. The practical risk lies in which state the gas system reads as safe: if a missing block signal were taken as permission, gas could be released when the controller wants it off, so controllers generally stop gas operation as soon as such a fault is confirmed. CARB requires every 2019 and later alternate-fueled vehicle to run under an approved monitoring plan, which is where checks like this belong. No manufacturer documents P25C0 publicly; the open circuit is P25BE, the high fault P25BF.
- What you may notice
- Vehicle refuses to switch to gas
- Fuel system fault message or flashing fuel indicator
- Check engine lamp
- Likely causes
- LikelyControl wire shorted to ground, often where routed along the frame
- PossibleChafed insulation on a retrofit gas kit harness
- RareOutput stage in the engine controller damaged
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.