P25F8Turbocharger/Supercharger Bypass Valve C Control Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Bypass valves in the intake let charge air flow around a compressor: on turbo engines they are the recirculation valves that open on a sudden throttle lift so the compressor does not surge, and on engines with a supercharger they can route air past the blower while it is idling or uncoupled. A third such valve, C, only appears on systems with several compressors; which valve gets the letter is manufacturer-specific. P25F8 is the general fault of its control circuit, typically an open circuit. No manufacturer documents P25F8. For valve A, Saab's GM-based 2.0 litre watches for open, short to ground or short to voltage for longer than 10 s at 11–32 V supply and sets a type B code. Expect surging noises on lift-off or less boost.
- What you may notice
- Check engine lamp on
- Fluttering noise when lifting off the throttle
- Less boost or slower response
- Likely causes
- LikelyBroken wire or loose connector at bypass valve C
- PossibleOpen coil in the valve or its solenoid
- RareSupply voltage missing (fuse, main relay)
- 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.