OBD-II code · Powertrain (generic)
P0234 Turbocharger/Supercharger "A" Overboost Condition
Boost pressure exceeded the upper limit during commanded full load. The ECU usually drops fuel and ignition or commands the wastegate fully open to protect the engine; persistent overboost can crack pistons or rings.
Is it safe to drive with P0234?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyWastegate stuck closed (carbon, broken linkage)
- PossibleBoost control solenoid failed
- PossibleVacuum/pressure line cracked
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1.5–8 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Turbocharger, Wastegate Actuator, Boost Pressure Sensor, Vacuum Lines
Related codes
- P0231Fuel Pump Secondary Circuit Low
- P0232Fuel Pump Secondary Circuit High
- P0233Fuel Pump Secondary Circuit Intermittent
- P0235Turbocharger/Supercharger Boost Sensor "A" Circuit
- P0236Turbocharger/Supercharger Boost Sensor "A" Circuit Range/Performance
- P0237Turbocharger/Supercharger Boost Sensor "A" Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.