P0242
Turbo/Super Charger Boost Sensor "B" Circuit High
- Severity
- Medium
- Driving
- Drive only to a garage
The boost sensor "B" signal is reading high - typically shorted to voltage or with a lost earth, though genuinely excessive boost will produce it too.
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