VW Eos TDI Idle Control Fix: IAC Valve Solutions

Similar issues occurred on my 2006 VW Passat TDI. Having moderate experience with car repairs, I initially thought it was just the idle control valve needing a basic cleaning. The engine stalling symptoms matched exactly what you describe, unstable idle speed and complete stalls at traffic lights. The air valve seemed like the obvious culprit, especially with those error codes. Took it to the workshop after attempting some basic troubleshooting. They found severe contamination in the entire intake system, not just the idle control components. The full cleaning service cost 425€ but solved the problem completely. The irregular idle disappeared and the car runs smooth again, even during cold starts. To help diagnose your case more precisely, could you share: Current mileage, When the idle speed issues first started, If the problem gets worse when the engine is cold, Whether you notice any smoke from exhaust, What specific error codes are stored This information would help determine if your intake system might have similar contamination issues or if other components of the idle control system need attention. Getting this fixed properly is important since continuous engine stalling can lead to unsafe driving situations and potentially damage other components.

Thanks for sharing your experience. My mileage is at 85197km and service history is up to date with the latest done 3 months ago. The issue started gradually over the past few weeks. No smoke from the exhaust, but I notice the unstable idle is worse during cold mornings. The engine stalling happens more frequently when the IAC valve seems to struggle regulating the idle speed. After reading your feedback about the intake system contamination, I am wondering if I should first try cleaning the throttle body before replacing parts. The irregular idle pattern sounds very similar to what you experienced. Would a thorough cleaning service likely resolve these symptoms, or should I prepare for a complete air valve replacement?

Based on your description and mileage, it strongly indicates intake system contamination similar to what I encountered. The cold morning symptoms particularly match my experience with the idle speed issues. Given your service history and gradual onset of problems, a complete cleaning service would be the most logical first step. The throttle body and IAC valve often accumulate carbon deposits that affect idle control, especially in TDI engines. My repair started with cleaning rather than immediately replacing parts. The service included: Thorough throttle body cleaning, IAC valve cleaning and testing, Complete intake manifold service, Air flow sensor inspection Total cost was around 425€ which proved more cost-effective than replacing components. The engine stalling issues resolved completely after cleaning, with stable idle speed restored even during cold starts. If cleaning doesnt resolve the irregular idle completely, then consider IAC valve replacement. But in my case, and many similar situations, aggressive carbon buildup was the root cause rather than failed components. Keep tracking the engine stalling frequency and idle behavior after any cleaning service. Sometimes it takes a few driving cycles for the idle control system to readjust after thorough cleaning.

Thanks everyone for the detailed input. After considering the advice and similar experiences shared, I think I will start with a professional cleaning service of the intake system before replacing any parts. The engine stalling symptoms and irregular idle behavior you described match my situation perfectly, especially regarding cold starts and IAC valve performance. Since my car has similar mileage and the idle control issues developed gradually like yours, contamination seems the likely culprit. I will book a thorough cleaning service for the throttle body and intake system first. The 425€ cost seems reasonable compared to replacing parts unnecessarily. Will update once I have the cleaning done to confirm if it resolves the stalling engine problems. Meanwhile, I will keep monitoring how the idle speed behaves, particularly during cold starts. Makes sense to track if the engine stalling gets worse while waiting for the service appointment. Thanks again for helping diagnose this, it gives me confidence to try cleaning before jumping straight to replacing the idle control components.