P25A6Fuel Mode Select Switch Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P25A6 means the fuel mode select switch signal has fallen below the range the module accepts. On a switch that pulls a reference line towards ground when pressed, this is the signature of a signal wire rubbed through to the body or of moisture bridging the switch contacts; a grounded line could otherwise pass for a button held forever. CARB requires input components to be checked for out-of-range values, which is what this code reports. No manufacturer documents P25A6 publicly, though GM's bi-fuel Impala and 2500HD trucks show where the switch lives: dash panel or centre stack, close to cup holders and accessory wiring. Unlike P25A7, the cause is a path to ground, so isolating the switch from its harness is the first test. Fuel selection by hand is lost.
- What you may notice
- Fuel mode cannot be changed
- Vehicle remains in one fuel mode
- Likely causes
- LikelySwitch signal wire chafed to ground behind the dash
- PossibleMoisture or spilt liquid bridging the switch contacts
- RareSwitch shorted internally
- 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.