Fault-Code Library · EGR
P0402: Exhaust-gas recirculation flow excessive
The ECU detects more EGR flow than requested, often because the valve is not closing correctly.
Common symptoms
- •Rough idle
- •Smoke
- •Poor response
- •Stalling
Likely causes
- •EGR valve stuck open
- •Carbon contamination
- •Airflow-sensor plausibility fault
- •Control or vacuum fault
First checks
- •Command the EGR while watching airflow
- •Inspect valve movement
- •Check MAF plausibility and intake restriction
Important
An EGR flow code can be caused by incorrect airflow measurement as well as the valve itself.
A fault code identifies a detected condition, not a failed part. Confirm manufacturer-specific subcodes and live data.
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