P0402
PPowertrainEGR Flow Excessive
What does this code mean?
Severity : MediumP0402 means the ECU measures excessive exhaust gas recirculation flow. Too much exhaust gas is being fed back into the intake, often because the EGR valve stays open when it should be closed. The air charge then lacks oxygen, which upsets combustion, especially at idle.
Symptoms
- Check engine light on.
- Rough idle or engine stalling.
- Hard starting.
- Loss of power and black smoke on diesels.
- Possible misfires on petrol engines.
Possible causes
- EGR valve held open by carbon deposits.
- Warped EGR valve plate or weak return spring.
- Control solenoid stuck energised.
- EGR position sensor giving a wrong reading.
- Short circuit in the valve control wiring.
Diagnosis and repair
- Check the actual EGR valve position in live data with the engine idling.
- Inspect the connector and wiring for a short circuit.
- Remove the valve and check that it closes fully.
- Clean the valve, or replace it if it does not seal.
- Clear the code and confirm with a road test.
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Code
P0402
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012