P0234
Turbo/Super Charger Overboost Condition
- Severity
- High
- Driving
- Drive only to a garage
The turbocharger or supercharger is producing more boost than the module allows. This is a protective code: too much boost raises cylinder pressure beyond what the engine was designed for, and the module cuts power to prevent damage. The engine will drop into a reduced-power mode, often abruptly and often just as you accelerate hard.
Possible causes
- CommonWastegate stuck closed, or its actuator seized
- CommonDisconnected or split boost control hose, so the wastegate is never opened
- CommonFailed wastegate control solenoid
- CommonVariable-vane mechanism seized with soot on a diesel
- PossibleFaulty boost sensor over-reporting
- PossibleAftermarket remap or boost controller raising boost beyond the standard limit
What you might notice
- Sudden loss of power under hard acceleration
- Limp mode
- Loud whistling from the turbo
- Check engine light on
- Power returning after a restart
What to check, in order
- Be aware that power can be cut abruptly. Avoid overtaking and motorway slip roads until this is fixed - the cut arrives exactly when you ask for full throttle.
- Check the boost control hoses for splits and disconnection.
- Check the wastegate actuator moves freely, and on a diesel that the variable-vane mechanism is not seized with soot.
- Ask whether the vehicle has been remapped or has a boost controller fitted. These raise boost past the module's limit and set this code by design.
- Do not keep driving hard with overboost. Sustained excess boost damages pistons, head gaskets and the turbo itself.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Fuel and air metering - injector circuits
P0200P0201P0202P0203P0204P0205P0206P0207P0208P0209P0210P0211P0212P0213P0214P0215P0216P0217P0218P0219P0220P0221P0222P0223P0224P0225P0226P0227P0228P0229P0230P0231P0232P0233P0234P0235P0236P0237P0238P0239P0240P0241P0242P0243P0244P0245P0246P0247P0248P0249P0250P0251P0252P0253P0254P0255P0256P0257P0258P0259P0260P0261P0262P0263P0264P0265P0266P0267P0268P0269P0270P0271P0272P0273P0274P0275P0276P0277P0278P0279P0280P0281P0282P0283P0284P0285P0286P0287P0288P0289P0290P0291P0292P0293P0294P0295P0296P0297P0298P0299