Engine and gearbox (P)
P0234: Turbocharger Overboost Condition
The engine control unit has detected that the boost pressure from the turbocharger is higher than the allowed target. This can lead to engine damage if not addressed.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Reduced engine performance
- Engine warning light on
- Possible engine knocking
- Increased exhaust smoke
Common causes
- Sticking vane mechanism
- Boost control fault
- Incorrect vacuum routing
How to check it yourself
- Check for any vacuum leaks or incorrect routing
- Inspect the turbocharger vane mechanism for sticking
- Test the boost control solenoid and actuator
- Compare the boost target with the actual boost pressure
Can I keep driving?
Avoid driving the car until the issue is resolved, as overboost can cause engine damage.
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