Engine and gearbox (P)
P0034: Turbo Bypass Valve Circuit Low
The control circuit for the turbocharger bypass valve is reporting a low voltage. This suggests there may be a short to ground or an open circuit, causing the ECU to disable boost control.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Reduced engine power
- Poor acceleration
- Check engine light on
- Possible whistling noise from turbo
Common causes
- Signal wire shorted to ground
- Solenoid internal short
- Connector pins corroded
How to check it yourself
- Inspect and clean connector pins
- Check wiring for shorts or damage
- Test the solenoid for internal shorts
Can I keep driving?
The car can be driven, but with reduced power and acceleration.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer