P0239
Turbo/Super Charger Boost Sensor "B" Circuit
- Severity
- Medium
- Driving
- Drive only to a garage
A fault in the turbocharger or supercharger boost sensor "B" circuit. This sensor tells the module how much boost pressure the charger is actually producing, and the module uses it to control the wastegate and to protect the engine. Without it the module will restrict boost rather than run blind.
Possible causes
- CommonFailed boost pressure sensor
- CommonCorroded or oil-contaminated connector
- CommonBlocked or split sensing hose
- CommonWiring damage in a hot part of the engine bay
- PossibleLoss of reference voltage or earth
- PossibleGenuinely wrong boost pressure - a leak or a failing turbo
What you might notice
- Reduced power or limp mode
- Poor acceleration
- Excessive smoke on a diesel
- Worse fuel economy
- Check engine light on
What to check, in order
- Watch the boost reading on the live data screen. With the engine off it should read close to atmospheric pressure - a reading far from that on a stationary engine proves the sensor wrong without any dismantling.
- Check the sensing hose for splits, blockage and oil.
- Inspect the connector for corrosion and oil.
- Check the reference voltage and earth before condemning the sensor.
- Check for boost leaks before assuming the sensor is lying - a split hose makes an accurate sensor report low boost.
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