Audi S4 Power Loss Points to Throttle Valve Problem

Having moderate experience with these issues, I dealt with almost identical symptoms on my 2013 Audi S5. The check engine light and reduced power output pointed to issues with the accelerator pedal module, which was causing significant response delay and putting the car into limp mode. Initially thought it was related to the air intake system, but my workshop ran diagnostics and confirmed it was the electronic module in the accelerator pedal assembly that was failing. The repair process was straightforward, they replaced the entire pedal module assembly. Total replacement cost came to 265 Euro including labor. The symptoms cleared up immediately after replacement, and fuel efficiency improved noticeably compared to when the issue was present. No more hesitation or reduced power problems since the fix. Before suggesting more specific solutions, could you share: Current mileage on your S4? Any recent changes or repairs to the engine management system? Does the issue occur more frequently when the engine is cold or warm? Have you scanned for specific error codes? This information would help determine if your case matches what I experienced with my S5.

Last service was at 174000km, about 2 months ago. The throttle response definitely feels sluggish, especially during engine idling. Had the codes scanned at a local shop and got P2015 and P2008. The engine performance seems worse when cold, usually takes about 15 mins of driving before it starts behaving somewhat normally. Really hoping its not a major repair as the response delay is making daily driving quite challenging. The limp mode activates out of nowhere, especially during highway merges which is concerning.

Thanks for providing those details. After seeing your error codes, I can confirm your symptoms do differ from what I initially experienced with my S5. Those specific codes (P2015 and P2008) typically indicate an intake manifold runner control issue rather than the accelerator pedal module I dealt with earlier. The cold-start symptoms and throttle sensor issues match what many others have reported with intake manifold problems. The throttle body itself might still be contributing to the issue, but the intake manifold should be checked first based on those codes. When my S5 had similar cold-start problems last winter, the repair shop found carbon buildup in the intake manifold causing irregular engine idling. The complete repair included: Cleaning the throttle body, Replacing intake manifold actuator, Updating the engine control software Total cost was around 850 Euro, but prices vary by region. The limp mode issues stopped completely after the repair, and cold-start performance returned to normal. Would recommend getting the intake manifold inspected soon, especially since you mentioned the unusual limp mode activation during highway merges. That safety feature kicks in to prevent potential engine damage when the throttle sensor detects irregular airflow patterns.

Thank you for that detailed feedback on the intake manifold issue. The error codes P2015 and P2008 really help narrow down the problem. Feels good to know others have dealt with similar symptoms and got them resolved through intake manifold repairs. The part about carbon buildup during cold starts matches exactly what I am experiencing with my S4. I will focus on getting the intake manifold checked first before looking at the throttle body. The cost estimate of around 850 Euro for the complete repair helps set realistic expectations. My main concern was the unusual limp mode during merges, but now understanding its a safety feature triggered by irregular air flow patterns makes more sense. Will book the car in next week to have the intake manifold inspected and likely cleaned or replaced. Really hoping this resolves both the cold start issues and the annoying response delay during normal driving. Thanks again for walking through your repair experience. The specific details about the manifold actuator replacement and software updates give me a clear picture of what to expect during the repair process.