Q7 Idle Control Issues: IAC Valve Under Suspicion

I experienced something very similar with my 2020 Q5. As someone with some experience working on cars, I initially thought it was just a simple IAC valve issue when my car showed unstable idle symptoms. After visiting the workshop, they performed a thorough diagnostic check of the idle control system. Turned out the entire throttle body and intake system was heavily contaminated, causing irregular air flow and engine stalling at idle. The repair included a complete cleaning of the intake system and throttle body service, which solved the idle problems completely. The total cost was 425 Euro. The unstable idle and stalling symptoms can indeed point to various issues in the intake system, but proper diagnosis is crucial before replacing parts. The IAC valve might not always be the root cause. To provide more specific advice for your case, could you share: Current mileage, Last service date, Whether the problems started gradually or suddenly, Any other symptoms besides the unstable idle, Any recent changes in fuel type or brand This information would help determine if your issue matches what I experienced or if it might be something different.

I just had my latest service done 2 months ago at 183749 KM. The stalling issues started gradually over the past few weeks. No other symptoms beyond the unstable idle and occasional stalling. Been using the same fuel type and brand consistently. Your throttle body cleaning experience is interesting, definitely worth checking before jumping straight to an IAC valve replacement. Did the engine stalling completely stop right after the cleaning in your case?

Thanks for providing those details, your situation sounds nearly identical to what I experienced with my Q5. The engine stalling issues completely resolved immediately after the throttle body cleaning. The idle control returned to normal, and I have not experienced any engine stalling since. The gradual onset of symptoms matches my experience perfectly, carbon deposits in the air intake system build up over time, slowly affecting the idle control. When my throttle body was cleaned, the technician showed me the significant carbon buildup that was disrupting proper air flow. In my case, even though the IAC valve was functioning correctly, the contamination was preventing proper idle control. A thorough cleaning proved to be a much more cost-effective solution than replacing components. The stable idle was restored, and the check engine light cleared after the service. Given your similar symptoms and maintenance history, I would strongly recommend having the intake system inspected for carbon buildup before considering IAC valve replacement. The cleaning service costs significantly less than a new valve, and in many cases, resolves the stalling issue completely.

Thanks for the detailed explanation about your throttle body cleaning experience. The similarities to my situation are quite striking. I will definitely have the workshop check the air intake system first before replacing any parts. Your feedback about immediate improvement in idle speed after cleaning is particularly encouraging. I called my regular workshop and scheduled an inspection for next week. Makes sense to start with checking for carbon buildup since the engine idle issues developed gradually, just like in your case. The potential cost savings compared to a full IAC valve replacement is also appealing. Will update this thread after the inspection to share what they find. This could help others experiencing similar car idle problems with their vehicles. Thanks again for sharing your experience with resolving these idle control issues, it has given me a clear direction for troubleshooting.