P25FA
Turbocharger/Supercharger Bypass Valve C Control Circuit High
Voltage on the third bypass valve control line is above the expected window. Typical causes are a short to battery or an open solenoid coil.
- 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.
- Control wire shorted to a B+ supplyCommon
- Open solenoid coilPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Bypass Valve C
- Bypass Solenoid
- Wiring Harness
P25FA 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.