P0034
Turbocharger Bypass Valve Control Circuit Low
The bypass valve solenoid control circuit reports a voltage below threshold, indicating a short to ground or open driver. The ECU disables boost control until the fault clears.
- Check engine light: Yes
- Emissions related: Yes
- 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.
- Signal wire shorted to groundCommon
- Solenoid internal shortPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Turbocharger Bypass Valve
- Wastegate Solenoid
- Wiring Harness
P0034 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.