P25FBTurbocharger/Supercharger Bypass Valve C Control Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P25FB is set when the control circuit of bypass valve C is not open or shorted, but its electrical behaviour does not match the command – for instance a current that rises too slowly or settles at the wrong level, or a signal that drops out now and then. That points to a coil whose resistance has changed with heat, contact resistance in the connector, or a valve whose armature moves sluggishly and so alters the current curve. Pure circuit faults are reported as P25F8 to P25FA, a valve that is mechanically stuck as P25FC. Which compressor valve C belongs to is decided by the manufacturer, and none documents this code publicly; CARB requires output components to be checked for proper function. Consequences range from surging on lift-off to reduced boost.
- What you may notice
- Check engine lamp on
- Occasional fluttering on lift-off
- Uneven boost build-up
- Likely causes
- LikelyValve coil resistance changed by heat ageing
- PossibleContact resistance or moisture in the valve connector
- PossibleSluggish valve armature due to deposits
- 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: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.