P0404 means the EGR valve is responding to ECU commands, but not within the expected position range. The ECU asks for a specific opening (say 30%) and the position sensor reports something different. Carbon buildup restricting valve travel is by far the most common cause.
DTC/P0404·Audi
P0404 on Audi: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Audi
P0404 on a Audi means the EGR valve is responding to ECU commands, but not within the expected position range. The ECU asks for a specific opening (say 30%) and the position sensor reports something different. Carbon buildup restricting valve travel is by far the most common cause.
Repair cost on Audi€85 - €1750
What does P0404 mean on a Audi?
Audi A4
2008–2024The A4 2.0 TDI (B8, B9) shares the EA189 and EA288 EGR setup with the Golf, so P0404 has identical root causes. The 3.0 TDI V6 (CCWA, CTBA codes) uses a more complex dual-bank EGR with separate position sensors per bank, and adaptation must be performed for both sides after service. VCDS or ODIS is required.
What causes P0404 on a Audi?
Beyond the generic causes listed on the main P0404 page, these are the Audi-specific patterns we see most often:
Audi A4EA189/EA288 carbon-restricted pintle travel identical to Golf
Audi A43.0 TDI V6 dual-bank adaptation needed after valve service
How to diagnose P0404 on a Audi with OBD2
Follow these steps to pinpoint the root cause of P0404:
- Use a scan tool to command the EGR valve through 0%, 25%, 50%, 75%, 100% and watch the position sensor feedback for delay or sticking
- Remove the valve and check for carbon buildup at the pintle and seat that limits travel
- Inspect the position sensor wiring and connector for corrosion or chafing
- Measure position sensor voltage at full closed and full open against the workshop spec
- After cleaning or replacement, perform the EGR adaptation procedure if the vehicle requires one (common on BMW, Mercedes, VAG)
How much does P0404 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 P0404 on Audi
These codes commonly cluster with P0404 on Audi vehicles:
FAQ: P0404 on Audi
What is the difference between P0403 and P0404?
P0403 is a pure electrical circuit fault (open, short, no response). P0404 means the circuit works, but the valve position does not match the commanded position. P0404 is almost always mechanical (carbon buildup, sticking pintle), while P0403 is usually electrical (solenoid, wiring, connector).
Can I drive with P0404?
Yes, short-term. Some modern diesels go into limp mode if the EGR cannot reach commanded positions, because the after-treatment calibration relies on EGR for NOx control. Plan the repair within a few weeks to avoid secondary DPF or SCR codes.
Will cleaning fix P0404 long-term?
On petrol engines, often yes if you also clean the intake manifold passages. On diesels with heavy soot output (BMW N47/B47, VAG EA189), cleaning may only last 20,000–40,000 km before the code returns. If the EGR cooler is degraded, replacement of the cooler-valve assembly is more durable.
Do I need to reset the EGR adaptation after replacing the valve?
Yes on most modern vehicles. BMW, Mercedes, and VAG all use stored adaptation values that must be reset and re-learned after a new EGR valve is fitted. INPA, VCDS, or a similar bi-directional scan tool is required. Skipping this step often causes the new valve to throw P0404 again within a few drive cycles.
Looking for the full P0404 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0404 guideSkanyx · Audi
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