EGR flow excessive on BMW diesel — N47/N57 stuck-open valve, often preceded by the well-known EGR cooler recall.
BMW P0402 — EGR flow excessive on BMW diesel — N47/N57 stuck-open valve, often preceded by the well-known EGR cooler recall. Typical UK independent garage cost: £350–£1200.
What actually causes P0402 on a BMW
N47/N57: BMW ran a global EGR cooler recall due to fire risk (cracked coolers vent hot exhaust into the airbox). Post-recall coolers are better but the valve still carbons up. Symptom of a stuck-open valve is P0402 plus rough idle when hot.
BMW engines that log P0402
- N47 2.0d (F30 320d, E90 320d)
- N57 3.0d (F10 530d, F30 335d)
- M47 2.0d (older 320d)
How we diagnose P0402 on a BMW
- VIN check for EGR cooler recall (Bimmerfest/dealer)
- ISTA live data — EGR commanded vs actual, MAF vs expected
- Remove EGR and swirl flap assembly, deep-clean
- Fit OE Pierburg valve; renew cooler if recall completed
The common misdiagnosis to avoid
Not checking the recall status — BMW will replace the EGR cooler free on eligible VINs. Also, don't clean the N47 EGR in situ; the intake manifold swirl flaps must come off to do it properly.
BMW P0402 repair cost in the UK
Expect £350–£1200 including parts and labour at an independent garage. Main-dealer quotes on BMW are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.
Bob's workshop tip
BMW N47 320d — check the EGR cooler recall FIRST. Free parts if eligible.
Codes usually seen alongside P0402 on BMW
- P0401
- P0403
- P244A
Symptoms drivers report with P0402
- Rough idle, often shaking the gear lever
- Hesitation off the line
- Stalling at junctions
- Possible black smoke at idle
- Engine warning light + power reduction warning
Repairs that clear P0402
- EGR clean or replace
- Sensor inspection
For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0402 guide.