P0403
Exhaust Gas Recirculation Control Circuit
- Severity
- Medium
- Driving
- Drivable — book it in
The module has found an electrical fault in the circuit it uses to control the EGR valve - the wiring, the connector, or the actuator winding itself. This is an electrical complaint rather than a flow complaint: the module is telling you it cannot reliably command the valve, not that it measured the wrong amount of gas.
Possible causes
- CommonCorroded or damaged connector at the EGR valve or solenoid
- CommonOpen or shorted winding in the EGR solenoid or valve motor
- PossibleChafed or heat-damaged wiring in the harness to the valve
- PossibleBlown fuse on the circuit feeding the valve
- RareFaulty control module driver circuit
What you might notice
- Check engine light on
- EGR system inoperative
- Failed emissions test
- Often no drivability symptom
What to check, in order
- Inspect the connector at the valve first. It lives in a hot, dirty part of the engine bay and corroded or heat-embrittled connectors are the usual cause.
- Measure the resistance of the solenoid or valve winding and compare it with the manufacturer's specification. Open circuit or near-zero both confirm a failed actuator.
- Check the wiring between the module and the valve for chafing where the harness passes near the exhaust or a bracket.
- Check for supply voltage at the valve connector with the ignition on.
- Suspect the control module only after the wiring, connector and actuator have all been eliminated. Module driver failure is real but uncommon.
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
Auxiliary emission controls
P0400P0401P0402P0403P0404P0405P0406P0407P0408P0409P0410P0411P0412P0413P0414P0415P0416P0417P0418P0419P0420P0421P0422P0423P0424P0425P0426P0427P0428P0429P0430P0431P0432P0433P0434P0435P0436P0437P0438P0439P0440P0441P0442P0443P0444P0445P0446P0447P0448P0449P0450P0451P0452P0453P0454P0455P0456P0457P0458P0459P0460P0461P0462P0463P0464P0465P0466P0467P0468P0469P0470P0471P0472P0473P0474P0475P0476P0477P0478P0479P0480P0481P0482P0483P0484P0485P0486P0487P0488P0489P0490P0491P0492P0493P0494P0495P0496P0497P0498P0499