Audi 2.0T Stalling: IAC Valve Common Culprit

I had a similar issue with my Audi A4 2.0T from 2015, and as someone with some hands-on experience working on these engines, I can share what worked for me. The symptoms were nearly identical, unstable idle speed and engine stalling. After taking it to my regular workshop, they diagnosed a heavily contaminated throttle body and IAC valve. The buildup was affecting the idle control system significantly. The repair involved: Complete cleaning of the throttle body, IAC valve replacement, Intake system cleaning, ECU reset and idle speed adjustment Total cost was 425 Euro for parts and labor. The engine idle has been perfect since the repair, and the check engine light never came back. Before suggesting specific solutions, could you share: What year is your A6? Have you noticed any other symptoms? When was the last time you had a throttle body cleaning service? Does the idle issue get worse after the engine reaches operating temperature? This information would help determine if your issue matches what I experienced, as these engines can develop similar idle control problems for different reasons.

Thanks for sharing your experience. My A6 is a 2017 model with 80928 KM. The idle speed issue is definitely worse when the engine is warm, and the stalling happens more frequently at stoplights. I just had my regular service last month but they didnt mention anything about the throttle body conditions. The check engine light started appearing about a week ago. The engine stalling became more frequent in the past few days, especially during slow speed maneuvering. When I give it some gas the engine runs smoothly, but the idle control seems completely off. Would cleaning the throttle body first be a good starting point before replacing parts?

Based on your description, this definitely sounds similar to what I experienced. Since your A6 has almost the same mileage as mine did when the issue occurred, I would strongly recommend starting with a thorough throttle body cleaning before replacing the idle air control valve. In my case, carbon buildup was affecting the throttle body operation, causing inconsistent idle control. A professional cleaning resolved about 70% of the idle issues, but the air valve itself needed replacement to completely fix the stalling engine problem. Quick tip: if you plan to clean the throttle body yourself, make sure to: Use proper throttle body cleaner, Clean both sides of the butterfly valve, Let it dry completely before reassembly, Perform an idle relearn procedure after cleaning The cleaning service typically costs around 150 Euro if done at a shop. If the stalling persists after cleaning, then replacing the idle control valve would be the next logical step, just like in my case. Have you noticed any rough running immediately after starting the car, or does it only begin after the engine warms up?

Since this is my issue, I need to reply to that last question to get more clarity. The rough running is mainly after warm-up, which matches what you experienced. Based on the costs you mentioned, I think I will start with the throttle body cleaning service since its more affordable than jumping straight to replacing the air valve. My only concern is the check engine light, should I get the codes read before proceeding with any cleaning, or is it safe to assume the air intake and idle control issues are triggering the light given all these symptoms? The stalling engine is becoming a real safety concern at intersections, so I want to get this resolved quickly but also want to make sure Im addressing the root cause. Ill schedule the throttle body cleaning this week and report back on whether it improves the idle speed issues. Thanks for explaining the repair progression, its helpful to know what worked in a similar situation.