The Quick Answer above is the generic definition. What follows is the model-specific detail for the Audi models that log P0404.
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.
Typical repair cost, all makes€68 - €1400
Connect any standard Bluetooth OBD2 adapter to your Audi and Skanyx tells you what P0404 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
Get Skanyx freeWhat 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 patterns noted for Audi models:
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 for P0404 in EUR, compiled across makes. Expect Audi parts and labour towards the upper end of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0404
These codes are often seen alongside P0404 or point to related issues, on any make:
Looking for the full P0404 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0404 guideSkanyx · Audi
Diagnose P0404 on your Audi
Your car logged P0404. Skanyx reads it on any standard Bluetooth OBD2 adapter, tells you whether it is safe to keep driving, and shows the €68-€1400 repair range so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.
Get Skanyx free