EGR flow excessive on Audi TDI — same EA189/EA288 carbon issue as VW, plus 3.0 TDI CR EGR cooler failures.
Audi P0402 — EGR flow excessive on Audi TDI — same EA189/EA288 carbon issue as VW, plus 3.0 TDI CR EGR cooler failures. Typical UK independent garage cost: £280–£1400.
What actually causes P0402 on a Audi
2.0 TDI: identical to VW — carbon-locked EGR valve. 3.0 TDI CR (V6 diesel): EGR cooler cracks internally and floods the intake with unmetered gas — sets P0402 with MAF discrepancy.
Audi engines that log P0402
- 2.0 TDI EA189 (A3, A4 B8, A6 C7)
- 2.0 TDI EA288 (A3 8V, A4 B9)
- 3.0 TDI CR (A6, A7, Q5)
How we diagnose P0402 on a Audi
- VCDS block 74/75 — EGR position and MAF flow
- Remove EGR valve, bench-clean and inspect seat
- 3.0 TDI CR: pressure-test EGR cooler
- Clean manifold, fit Pierburg OE valve
The common misdiagnosis to avoid
3.0 TDI CR — replacing the valve without inspecting the cooler wastes £400. Always pressure-test the cooler on V6 diesel.
Audi P0402 repair cost in the UK
Expect £280–£1400 including parts and labour at an independent garage. Main-dealer quotes on Audi 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
A6 3.0 TDI — always pressure-test the EGR cooler before condemning the valve.
Codes usually seen alongside P0402 on Audi
- P0401
- P0403
- P042F
- 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.
Reading P0402 on a Audi properly
A generic reader will show P0402 and nothing else. What matters is the freeze-frame data stored with it — engine speed, load, coolant temperature and fuel trims at the moment the fault was logged — plus whether any other module on the Audi has logged something at the same time. Codes rarely arrive alone, and the order they were stored in usually points at which one is the cause and which are the consequences.
Clearing P0402 without fixing it
Erasing the code resets the Audi's readiness monitors as well as the light. The fault returns on the next drive cycle if the cause is still there, and in the meantime the incomplete monitors can stop the car passing an emissions check. After a genuine repair, the car is driven until the relevant monitor completes before it is handed back.
Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P0402 is showing on your Audi, bring any scan results with you — we will read the live data ourselves, confirm which cause it actually is, and price the repair before any work starts.