S6 Power Loss + CEL Points to Faulty Temp Sensor

Recently dealt with similar symptoms on my 2017 S4. The exhaust system was indeed the source of the problem, but it wasnt just the temperature sensor. A comprehensive diagnostic revealed multiple failing components. The exhaust leak was causing incorrect readings from both heat sensors, triggering the check engine light and forcing the engine into safety mode, hence the power loss. The ECU was getting false temperature data and running a rich fuel mixture to protect the engine, explaining the increased fuel consumption. The repair required replacing two temperature sensors and fixing a cracked exhaust component near the catalytic converter. This was a serious issue that needed immediate attention, as continuing to drive could have led to catalyst damage and even more expensive repairs. The symptoms match perfectly with your S6. Would strongly recommend finding a shop that specializes in Audi exhaust systems, as proper diagnosis requires specific knowledge of where these sensors are located and how they interact with the engine management system. A basic sensor replacement might solve the issue, but given the mileage, having the entire exhaust system inspected would be prudent. The exhaust components often wear out around this mileage point.

Thanks for sharing your experience. My S6 showed identical symptoms last winter. Having a specialist check the emission control system was definitely the right call. The exhaust sensor replacement fixed most issues, but they also found some wear on the catalytic converter that needed attention. Did you remember roughly what you paid for the full repair? Also curious if youve had any other sensor issues since the fix?

Got my S4 all sorted now, went to see a specialist who diagnosed and fixed the problem. My exhaust temperature sensor was indeed faulty, causing those erratic engine management readings we both experienced. The total repair came to 265 Euro, which covered fixing a sneaky leak they found in the exhaust system. Since the repair three months ago, the engine management system has been running perfectly with no sensor issues whatsoever. The power is back to normal and fuel consumption has returned to what it should be. Really glad I had the entire exhaust system checked out, as catching that leak early probably saved me from more expensive repairs down the line. The investment in proper diagnostics and repair was worth every cent, no more check engine lights or performance problems. If you notice any other sensor-related issues though, best to get them checked right away while theyre still minor.

Thanks for the input. Finally took my S6 to a new specialist shop last week and got everything sorted. The exhaust temperature sensor was definitely shot, just as suspected. They found the sensor was giving false readings which explained the power loss and fuel consumption issues. The repair came to 310 Euro total, slightly more than expected but they also fixed a small exhaust leak near the catalytic converter that I didnt even know about. The car runs like new now, full power is back and fuel consumption is normal again. Really glad I had them check the entire exhaust system while they were at it. After dealing with this, my advice to others would be dont wait if you notice similar symptoms. A failing heat sensor can cause the engine to run rich and potentially damage other components if left unchecked. Going to a shop that knows their way around modern exhaust systems was definitely worth it.