VW Virtus Stalling: IAC Valve Symptoms & Fix Guide

Having experienced similar symptoms on my 2015 VW Polo TSI, I can relate to this idle problem. The main issue turned out to be severe carbon buildup in the throttle body and air intake system. The symptoms matched exactly: unstable car idle, engine stalling at traffic stops, and rough running. The check engine light also indicated problems with the air-fuel mixture. The fix required: Complete throttle body cleaning, Air intake system decontamination, IAC valve inspection and cleaning, Recalibration of the idle air control system This was a serious issue that needed immediate attention, as continued operation could have led to additional engine performance problems and potentially damaged other components. When discussing with a mechanic, request: 1. Full diagnostic scan 2. Inspection of the throttle body contamination 3. Air intake system cleaning 4. Testing of the IAC valve operation 5. Checking for vacuum leaks The issue took about 4-5 hours to resolve properly. While carbon buildup is common, neglecting it can lead to more expensive repairs later. Regular maintenance could have prevented this level of contamination.

Thanks for sharing the detailed solution for the stalling engine issue. My Virtus had almost identical problems with the idle speed and check engine warnings. Would like to know how much you ended up paying for all that work? After the repairs, did you notice any other issues or has the car been running smoothly? In my case, the unstable idle turned out to be from both a faulty IAC valve and significant carbon deposits. The air valve system definitely needed a thorough cleaning. Just wondering if the fix has been permanent for you or if you needed any follow-up repairs.

My VW is running perfectly now after getting the repairs done. The idle air control valve was definitely bad and needed replacement, plus the air intake system was heavily contaminated. Total cost came to 425€ for everything, including the thorough cleaning and new IAC valve. The engine idle is completely stable now, no more stalling or rough running issues. It starts smoothly and maintains steady idle even in cold weather. The check engine light has stayed off since the repair. The mechanic showed me how clogged the intake system had become, which explained the erratic idle behavior. After cleaning out all that carbon buildup and installing the new valve, the difference in performance was immediately noticeable. Been about 6 months now with no issues returning. Regular maintenance should prevent similar problems from developing again. The stable idle and smooth running make it clear the repair was worth every cent. If your symptoms match what I experienced, getting both the IAC valve and intake system checked is definitely the right approach. The combined fix seems to be a permanent solution rather than just treating individual symptoms.

Thanks for the helpful advice. I took my car to a new mechanic yesterday after reading these responses. They confirmed it was carbon buildup plus a faulty IAC valve causing the unstable idle and stalling issues. The total repair came to 390€ which included: New IAC valve, Complete intake system cleaning, Throttle body service, Diagnostic testing The engine idle is perfectly smooth now and no more stalling at traffic lights. The check engine light is off and the car runs great. The mechanic showed me all the carbon deposits they cleaned out, it was pretty bad. Really glad I asked here first and knew what to discuss with them. They were upfront about the costs and explained everything they were doing. Much better experience than my previous mechanic. Will definitely keep up with regular maintenance to prevent this happening again.