P0402 means the EGR system is flowing too much exhaust gas back into the intake manifold. The most common cause is an EGR valve stuck partially open, often due to carbon buildup on the valve seat. Diesel engines are especially vulnerable because of higher soot output.
DTC/P0402·Audi
P0402 on Audi: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Audi
P0402 on a Audi means the EGR system is flowing too much exhaust gas back into the intake manifold. The most common cause is an EGR valve stuck partially open, often due to carbon buildup on the valve seat. Diesel engines are especially vulnerable because of higher soot output.
Repair cost on Audi€85 - €1750
What does P0402 mean on a Audi?
Audi A4
2008–2024The A4 2.0 TDI (B8 and B9 chassis) shares EA189 and EA288 engines with the Golf and suffers identical EGR carbon issues. The valve is harder to access on the A4 due to tighter engine bay packaging, which pushes labor costs higher. On 3.0 TDI V6 models, the dual EGR coolers add complexity and parts cost when failure occurs.
What causes P0402 on a Audi?
Beyond the generic causes listed on the main P0402 page, these are the Audi-specific patterns we see most often:
Audi A4EA189/EA288 carbon buildup with tighter engine bay access on B8/B9
Audi A43.0 TDI V6 dual EGR cooler assembly failure (higher parts cost)
How to diagnose P0402 on a Audi with OBD2
Follow these steps to pinpoint the root cause of P0402:
- Read freeze frame data and check whether the fault appears at idle, cruise, or under load
- Remove the EGR valve and inspect the seat and pintle for carbon buildup preventing full closure
- Command the EGR valve closed with a scan tool and verify it seats fully (position sensor should read 0%)
- Inspect vacuum hoses (vacuum-operated systems) for leaks that hold the valve cracked open
- On diesel engines, inspect the EGR cooler for internal damage and verify the MAP sensor reads correctly against a known-good reference
How much does P0402 cost to fix on a Audi? (EUR)
Estimated repair costs on a Audi (Audi parts and labour typically run 25% above the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0402 on Audi
These codes commonly cluster with P0402 on Audi vehicles:
FAQ: P0402 on Audi
Can I drive with P0402?
Short distances yes, but expect rough idle and possible stalling. Excessive EGR flow dumps soot and exhaust into the intake, which accelerates carbon buildup on intake valves, especially on direct-injection engines. Get it diagnosed within a few weeks.
Is EGR delete legal in the EU?
No. EGR delete is illegal across the EU and UK. It increases NOx emissions, triggers a permanent check engine light, fails the periodic technical inspection (TÜV in Germany, ITV in Spain, TA in Lithuania, SKP in Poland), and can result in vehicle deregistration. Stick to cleaning or replacement.
Will cleaning the EGR valve fix P0402?
Often yes. P0402 is usually caused by carbon stopping the valve from closing fully. Removing the valve, soaking it in EGR cleaner or carb cleaner, and clearing the seat resolves the code on roughly half of cases. If the solenoid or motor itself has failed, replacement is needed.
Why does my diesel keep throwing P0402 after cleaning?
Diesel engines produce far more soot than petrol, so the EGR valve re-fouls quickly. If the EGR cooler is also blocked or leaking internally, the valve will stick open again within months. On heavily affected engines (BMW N47, M57), the cooler often needs replacement alongside the valve.
Looking for the full P0402 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0402 guideSkanyx · Audi
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