P0234: Turbocharger/Supercharger "A" Overboost Condition
P0234 means Turbocharger/Supercharger "A" Overboost Condition. Boost pressure from the turbocharger or supercharger is higher than the engine computer commanded.
Can I keep driving? Limit driving and diagnose promptly. Continued driving can cause damage, stalling or limp mode.
Common symptoms
- Check engine light on
- Power surging, then limp mode
- Possible engine knock
Possible causes
- Wastegate stuck closed or seized actuator
- Split or disconnected wastegate/actuator vacuum hose
- Sticking variable-geometry turbo vanes
- Faulty boost control solenoid
- Faulty boost pressure sensor
How to diagnose P0234
- Compare desired and actual boost on a scan tool.
- Check the actuator moves freely and its hoses are intact.
- Test the boost control solenoid.
- Check the boost pressure sensor reading with the engine off (should be close to barometric pressure).
Overboosting can damage the engine. Avoid full throttle until this is fixed.
What the code means, digit by digit
Generic codes have the same definition on every OBD-II vehicle (petrol cars from model year 1996 in the US, 2001 in the EU; diesels later). Manufacturers can add their own enhanced codes; those are not listed here.
General guidance only. Fault codes describe what the engine computer saw, not which part failed: confirm with testing before replacing parts, and follow the vehicle's service information.