P0402 EGR flow excessive detected
What P0402 means
The engine control unit has measured more recirculated exhaust gas entering the intake than it asked for. Too much EGR dilutes the air charge, so the engine idles roughly, hesitates or may stall, and diesels can smoke.
P0402 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 80–600 €
- Workshop time
- 1–5 h
- Repair difficulty
- Medium
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Rough or unstable idle
- Stalling when coming to a stop
- Hesitation and loss of power
- Black smoke on diesels
Common causes
- EGR valve stuck partly open by carbon deposits
- Faulty EGR valve or control solenoid
- Faulty EGR position sensor or differential pressure feedback sensor
- Leaking or incorrectly routed vacuum hoses to a vacuum-operated EGR valve
Can I keep driving with P0402?
You can drive, but book a workshop visit within a week. If the engine stalls at junctions, avoid heavy traffic until it is fixed.
What to check first
- Read freeze-frame data and compare commanded and actual EGR position in live data
- Remove and inspect the EGR valve; clean carbon from the valve and its seat
- Check vacuum hoses and the control solenoid on vacuum-operated systems
- Replace the EGR valve if it still does not close fully after cleaning
Related codes
- P0401 Exhaust gas recirculation (EGR) A flow insufficient
- P0403 EGR A control circuit/open
- P0400 Exhaust gas recirculation (EGR) A flow malfunction
- P0404 EGR A control circuit range/performance
- P0405 EGR sensor A circuit low
- P0406 EGR sensor A circuit high
- P0410 Secondary air injection system A
- P0411 Secondary air injection system incorrect flow detected
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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