P25F8
Turbocharger/Supercharger Bypass Valve C Control Circuit
A third bypass (recirculation or wastegate) valve used in three-stage charging systems is not responding to control commands. Boost balancing across stages can no longer be achieved.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
Common causes
Ordered by how often each turns out to be the cause.
- Open solenoid coilCommon
- Open or shorted wiring to the valvePossible
Parts involved
- Bypass Valve C
- Bypass Solenoid
- Wiring Harness
P25F8 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.