Audi S3 Power Loss Linked to Exhaust Sensor Issues

Having some experience with Audi repairs, I encountered a similar issue with my 2012 Audi S4. The symptoms you describe match exactly what I experienced, reduced power, higher fuel consumption, and that annoying check engine light. In my case, after inspection, it turned out there was a significant leak in the exhaust system near the connection points. The exhaust temperature sensor readings were off because of the leak, causing the engine management system to adjust fuel mixture incorrectly. The repair involved replacing damaged exhaust components and gaskets, costing 265 Euro in total. After fixing the leak, all symptoms disappeared immediately and fuel economy returned to normal. Before jumping to conclusions though, could you share: Any unusual sounds from the exhaust system? Does the engine sound different than usual? Have you noticed any unusual exhaust smell? When exactly did the check engine light first appear? The exhaust sensor might indeed be the culprit, but based on my experience, its often worth checking the entire exhaust system for leaks first. Temperature fluctuations can sometimes be a symptom rather than the root cause.

Current mileage: 121712 KM Last service: Regular maintenance performed at 120000 KM Thanks for the detailed reply about the exhaust component issues. After reading your message, I did notice a slightly rougher sound from the exhaust system, especially during cold starts. The check engine light first appeared about 2 weeks ago, and there is a slight sulfur smell that was not present before. The temperature sensor diagnosis makes more sense now given these symptoms. I will have my mechanic perform a complete exhaust system inspection to check for any leaks before replacing the sensor. The engine management system readings should definitely be rechecked after fixing any potential leaks. Has anyone else found the repair costs to be higher than the quoted 265 Euro? Want to budget appropriately for potential exhaust system work.

Your exhaust leak situation does sound very similar to what I experienced with my S4. After my initial repair of the exhaust components and gaskets for 265 Euro, I actually discovered a related issue a few months later. The sulfur smell you mentioned, I had that too. In my case, while the initial leak was fixed, the faulty readings had already damaged the temperature sensor. The sensor replacement became necessary after all, adding another 180 Euro to the total repair cost. Based on the symptoms you describe, especially that sulfur smell and rough cold starts, you might be looking at both issues: exhaust leaks and a compromised temperature sensor. The heat sensor can fail when exposed to irregular exhaust flow for extended periods. A complete exhaust system inspection is definitely the right approach. When factoring in your budget, I would plan for: Basic exhaust repair: 250-300 Euro, Sensor replacement if needed: 150-200 Euro, Labor costs: 100-150 Euro My total repairs ended up around 445 Euro including both the exhaust component fix and sensor replacement. The investment was worth it though, fuel consumption dropped back to normal and engine performance was fully restored.

Thanks to everyone who shared their repair experiences. After taking my S3 to the shop today, the diagnosis confirmed both a minor exhaust leak and a faulty heat sensor. The total repair estimate came to 480 Euro, which aligns with the costs mentioned here. The mechanic found the exhaust system leak near the connection points, similar to what was described. They recommended replacing both the damaged exhaust components and the temperature sensor in one service to prevent future issues. This makes sense given how the sensor readings were affected by the leak. Going to proceed with the full repair next week. The exhaust sensor replacement and system fix should resolve both the performance issues and that sulfur smell. Really helpful to know others had similar experiences with their Audis and got everything sorted with comparable repair costs. Will update after the service if anything unexpected comes up during the exhaust system repair. For now, I feel much more confident about the diagnosis and repair approach.