RS4 Idle Control Valve Failure Causing Random Stalls

Had a very similar issue with my S4 (2011) last year. Having some experience with engine management systems, I initially thought it was just the idle control valve too. The stalling engine symptoms matched exactly what you describe, unstable idle speed and complete stalls when coming to a stop. After scanning, my workshop found the throttle body and entire air intake system were heavily contaminated, restricting proper airflow at idle. The complete cleaning of the intake system, including the throttle body, resolved the engine idle issues completely. Total cost was 425 Euro for diagnostics, cleaning, and recalibration. Much better than replacing parts unnecessarily. Could you share: Build year of your RS4, Current mileage, When you last had the air intake system serviced, Any modifications to the intake system This would help determine if you might be dealing with the same root cause. Idle problems often stem from air intake issues rather than just the control valve itself.

Last service was done at 195000 KM and included oil change plus basic inspection. My 2006 RS4 with 197712 KM is mostly stock with no intake modifications. You might be onto something with the throttle body cleaning suggestion. The car did sit unused for a few months last winter, which could have contributed to carbon buildup affecting the idle speed. The stalling engine issue started shortly after getting it back on the road regularly. I checked the service records and realize the intake system has never had a proper cleaning service in my ownership period. Definitely worth investigating before replacing the idle control valve. Based on the stable performance at higher RPMs, your diagnosis about dirty throttle body affecting the engine stalling makes a lot of sense.

Thanks for the detailed info. Looking back at my S4 experience, the symptoms are remarkably similar, especially considering both cars were inactive for extended periods. The carbon buildup tends to be more problematic in direct injection engines like ours. After cleaning my throttle body and IAC valve, the idle speed stabilized completely. Even now, a year later, the engine maintains perfect idle. A few tips from my experience: Have the entire intake tract cleaned, not just the throttle body, The IAC valve might need recalibration after cleaning, Get the idle control parameters reset via diagnostic tool, Consider using intake cleaner additives for prevention The total repair cost should be similar to what I paid (425 Euro), which is far cheaper than replacing the idle control valve. The stalling engine issue hasnt returned since the cleaning. Given your mileage and the storage period, this maintenance would be highly beneficial even if it turns out not to be the main cause of your idle problems.

My update on the idle issue, got the car checked today and was absolutely right. The workshop found significant carbon deposits in the air intake system and throttle body. They did a thorough cleaning service for 390 Euro, which included recalibrating the idle control settings. The engine idle is now perfectly stable with no more stalling issues. The check engine light cleared after they reset the system. The mechanic showed me the before and after pictures of the throttle body, the buildup was pretty severe, definitely affecting the airflow at low RPMs. For anyone else experiencing similar engine stalling symptoms, especially after periods of inactivity, checking the air intake system first makes a lot of sense. The repair cost was reasonable compared to replacing parts, and the improvement in idle performance is significant. Will definitely keep up with regular intake cleaning from now on to prevent future idle control problems. Thanks for steering me in the right direction and saving me from unnecessary parts replacement.