VW Throttle Body Issues Causing Rough Idle & High Fuel Use

As someone with moderate experience working on VWs, I had a similar issue with my 2006 Polo. The symptoms you describe match exactly what I experienced, poor throttle response, high fuel consumption, and unstable idle. The throttle position sensor in my case was acting up, causing the engine management system to receive incorrect readings. This led to poor fuel efficiency and rough running. After some initial attempts at cleaning the throttle valve, which only provided temporary relief, I had to get the accelerator pedal module replaced as it was the root cause. The repair took about 2 hours at my regular workshop, costing 205€ including parts and labor. Since the fix, the air intake system works perfectly, and fuel consumption returned to normal levels. Before jumping to conclusions though, could you share: Any check engine lights showing? Does the car stall when coming to a stop? Have you noticed if the throttle response is worse when the engine is cold or warm? Did you scan for error codes? This information would help determine if your issue matches what I experienced with my car. Sometimes cleaning the throttle body helps, but if its the pedal module like in my case, only replacement will solve it permanently.

I had my last service at 98000km and already checked the error codes. No engine lights are showing currently. The throttle response is definitely worse when the engine is cold, and yes, it occasionally stalls at stops. The car runs smoother after warming up, but fuel consumption remains high. I cleaned the throttle body as suggested but only got minimal improvement. Control valve replacement might be necessary based on these continuing symptoms.

Thanks for providing those details. My Polo had the exact same behavior, running rough when cold and stalling at stops, just like yours. The temporary improvement after throttle cleaning matches my experience too. Since the symptoms persist after cleaning and match the cold-running issues, this strengthens my original suspicion about the accelerator pedal module. The control valve system is likely struggling to maintain proper air intake management, especially during cold starts. In my case, waiting too long to fix it led to even higher fuel consumption. Once I replaced the pedal module and had the throttle cleaning done professionally, the engine idle stabilized completely. The difference in fuel efficiency was noticeable within the first tank. Key indicators that convinced me it was the pedal module: Improved running after warm-up, Stalling at stops, Minimal effect from throttle cleaning, No check engine lights, Poor cold-start performance Since your symptoms are identical to what my Polo displayed, I strongly recommend getting the pedal module checked. The investment in proper diagnosis and repair will pay off through restored fuel efficiency and smoother operation. Have you noticed any vibration or hesitation when pressing the accelerator? This could help confirm if we are dealing with the same root cause.

Thanks for the additional input. Yes, I definitely notice hesitation when pressing the accelerator, especially from a standstill. The throttle position seems really inconsistent, sometimes it responds normally and other times there is a noticeable lag. Based on the matching symptoms and your experience, I will get the accelerator pedal module checked. The engine throttle behavior matches exactly what you described with your Polo, particularly the cold start issues and poor response. Since the throttle cleaning only provided minimal improvement, replacing the control valve and pedal module seems like the logical next step. I will book it in next week for diagnosis and likely repair. The 205€ cost you mentioned seems reasonable considering the potential fuel savings. Better to fix it now before the engine throttle issues get worse or cause additional problems. Will update once I have it sorted to confirm if this was indeed the same underlying issue.