P0231
Fuel Pump Secondary Circuit Low
- Severity
- High
- Driving
- Drive only to a garage
The fuel pump secondary circuit is reading low - typically shorted to earth or an open circuit. This is the heavy side of the circuit, carrying the current that actually drives the pump. Depending on the fault the pump may run weakly, not at all, or run when it should not.
Possible causes
- CommonFailed fuel pump relay
- CommonBlown fuse on the fuel pump circuit
- CommonCorroded connector at the fuel pump or in the boot floor
- CommonFailed fuel pump
- PossibleDamaged wiring under the vehicle
- PossibleCorroded earth at the pump
- RareFailed control module driver
What you might notice
- Engine will not start
- Cutting out while driving
- Loss of power under load
- No fuel pump noise when the ignition is switched on
- Check engine light on
What to check, in order
- Check whether the low reading persists with the relay removed. That separates the relay from the pump and its wiring.
- Listen for the pump. Switch the ignition on without cranking and listen at the fuel tank - a working pump runs for a second or two. Silence is a clear finding and costs nothing to check.
- Check the fuse and swap the relay with an identical one from elsewhere in the box.
- Check for battery voltage at the pump connector while the pump should be running.
- Check the pump earth connection - a corroded earth produces the same symptoms as a failed pump.
- Inspect the wiring under the vehicle for corrosion and impact damage.
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