P25FC
Turbocharger/Supercharger Bypass Valve C - Mechanical
The third bypass valve is mechanically jammed. Solenoid is energised correctly but the valve flap or disc does not move as expected.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Common causes
Ordered by how often each turns out to be the cause.
- Carbon buildup blocks the valve flapCommon
- Actuator linkage seized by corrosionPossible
Parts involved
- Bypass Valve C
- Actuator Linkage
P25FC is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.