Audi S3 Starting Issues Point to Failing Throttle Body

Had similar issues with my 2003 Audi A4 1.8T. The symptoms matched exactly, poor fuel consumption and rough starts. The problem turned out to be a failing throttle body assembly, specifically the control valve and throttle position sensor components. The repair required replacing the complete throttle body unit. The engine throttle symptoms became more apparent over time, rough idling, delayed response when pressing the accelerator, and the check engine light eventually came on. The air intake system was also cleaned during the service to ensure optimal performance. This was a serious issue that needed immediate attention, as a malfunctioning throttle body can lead to complete engine failure or leave you stranded. The repair took about 4 hours at the shop. After replacement, the car returned to normal performance with improved fuel efficiency and smooth acceleration. Would strongly recommend having the throttle position sensor tested first, as diagnostic tools can quickly identify if this is the source of the problem. If the throttle body needs replacement, make sure to get an OEM part for proper compatibility.

Thanks for sharing your experience. My throttle body issue got fixed last month and the symptoms were identical. The car throttle was sticking and causing those exact starting problems and efficiency drops. The cleaning of the throttle valve initially helped but the issues came back within days. Had to replace the entire throttle body assembly since the electronic throttle position sensor was shot. Did you keep track of the repair cost? Just curious how it compares to what I paid. Also wondering if youve had any other issues pop up since the fix?

Thanks for the follow-up. Since getting the throttle body replaced and fixing the defective accelerator pedal module which cost 205 Euro, my engine idle has been perfect with no issues whatsoever. The investment was worth it, as the car throttle response is now crisp and fuel efficiency is back to normal levels. The throttle cleaning they initially attempted would have saved money, but like in your case, a complete replacement was ultimately necessary when the throttle position sensor failed completely. The electronic controls in these units tend to wear out over time. No other related problems have surfaced in the past 18 months since the repair. The engine runs smoothly, starts reliably in any weather, and maintains steady idle. Regular maintenance and keeping the air intake system clean has helped prevent any recurrence of throttle issues.

Just got back from the mechanic yesterday actually. After your response matched my symptoms so closely, I went straight to a specialist shop. The technician confirmed the throttle position sensor was failing after running diagnostics. Total repair came to 380 Euro including parts and labor. They replaced the entire throttle body unit since the control valve showed signs of wear too. The fuel efficiency improvement was immediate, probably saving 2-3 liters per 100km now. The engine throttle response feels completely different, much smoother acceleration and no more rough starts in the morning. Really glad I caught this before it left me stranded somewhere. Thanks for helping me identify the issue and giving me confidence to push for the right repair.