Audi A3 Stalling Issue Points to Idle Control Valve

I had a similar issue with my Audi A4 2.0 TSI from 2015. The engine idle was extremely unstable, and the stalling engine problem got worse over time, especially when the engine was warm. After some initial misdiagnosis, my workshop found the root cause: the throttle body and air valve system were heavily contaminated. The carbon buildup was causing irregular airflow, leading to the unstable idle speed. The complete fix included: Professional throttle body cleaning, Air intake system decontamination, Idle control valve replacement, System recalibration Total cost was 425 Euro for parts and labor. Since the repair, the engine idle has been smooth and the check engine light hasnt returned. To better assist with your case, could you share: Current mileage, When was the last throttle body service, Any other symptoms besides stalling, Does the stalling happen more frequently in specific conditions (cold/hot weather, AC on/off) Regular throttle body cleaning is often overlooked in maintenance schedules, but its crucial for these engines to prevent stalling issues.

Thanks for sharing your experience. I have 156474 KM on the clock, and after seeing your reply, I suspect we have the same problem. My IAC valve symptoms match yours exactly, unstable idle and stalling engine issues, particularly after warmup. I checked my service records and noticed the throttle body was never cleaned since I got the car. Will definitely get both the cleaning and IAC valve checked. The 425 Euro cost seems reasonable for the complete fix. By the way, my car also runs rough when the AC is on, another sign pointing to the air valve system.

Thanks for the additional details. Those symptoms definitely mirror what I experienced with my A4. The AC issue you mentioned is particularly telling, my car also had a noticeable rough idle when the AC was running, which completely disappeared after the air valve system service. With your mileage at 156474 KM and no previous throttle body cleaning, carbon buildup is almost certainly contributing to your engine stalling issue. My idle problems started around similar mileage. Quick tip from my experience: while they were doing the idle air control valve replacement, I had them perform a complete air intake system cleaning. The technician showed me the carbon deposits they removed, it was shocking how much buildup had accumulated, seriously restricting proper airflow. You might want to consider getting the mass airflow sensor checked too, it was relatively clean in my case, but Ive heard from others that it can also affect idle speed when dirty. The diagnostic for this was included in my 425 Euro service cost. Would definitely recommend getting it sorted soon, my engine stalling got progressively worse before I had it fixed, and these issues rarely resolve themselves.

Your symptoms match what I experienced, unstable idle speed and engine stalling, especially after warm-up. The air valve issues and rough running with AC match my situation exactly. My mileage is 156474 KM and checking my records shows no throttle body service was ever done. This plus your experience confirms I should get both the cleaning and idle control valve checked. The 425 Euro price point for the complete fix seems fair. One thing I forgot to mention, when the AC is running the engine also starts running really rough at idle. This seems to be another typical symptom of air valve system problems based on your description. The throttle body cleaning and system recalibration you suggested makes a lot of sense given the age and mileage. Will book it in for service next week before the engine stalling gets any worse. Thanks for the detailed information about what to expect with the repair.