Audi TFSI Power Loss Linked to Faulty Heat Sensor

Having faced a similar issue with my 2014 Audi A4 2.0 TFSI, I can share my experience with exhaust sensor problems. I have some experience working on basic car maintenance, but sensor issues require professional diagnosis. The symptoms you describe match what I encountered, check engine light, power loss, and increased fuel consumption. My workshop performed a complete diagnostic scan that revealed a leak in the exhaust system near the temperature sensor, causing incorrect readings and performance issues. The repair involved: Full diagnostic scan, Visual inspection of the exhaust system, Replacement of the faulty exhaust sensor, Repair of the small leak in the connecting pipe Total cost was 265 Euro, including parts and labor. The repair resolved all symptoms and the car has been running smoothly since. Before suggesting specific solutions, could you share: Have you noticed any unusual exhaust sounds? Did the temperature fluctuation start gradually or suddenly? Are there any other warning lights besides the check engine light? Have you had any recent exhaust system work done? This information would help determine if your issue matches what I experienced with my A4.

Thanks for sharing your experience. My A3 recently had its service at 82412 KM, and the engine management system started showing these issues shortly after. The exhaust temperature sensor problems appeared quite suddenly, no unusual sounds from the exhaust system before the check engine light came on. The power loss was immediate and very noticeable, especially during acceleration. I had a local mechanic take a quick look, and while he confirmed the temperature sensor readings were off, he wanted a second opinion before proceeding with repairs. No other warning lights have appeared on the dashboard, and the exhaust system has not had any previous work done. Your repair costs sound reasonable, good to have a baseline figure before heading to the workshop. The diagnostic steps your mechanic took seem thorough, especially checking for leaks in the surrounding exhaust components.

The progression of symptoms in your A3 sounds identical to what I experienced with my A4. Having that sudden onset right after service raises a flag, as sometimes disturbing the exhaust system components during maintenance can trigger these issues. When my engine management system started acting up, the immediate power loss was exactly as you describe, most noticeable during acceleration. The fact your mechanic already confirmed irregular temperature sensor readings matches my diagnostic journey perfectly. For my A4, the leak near the sensor turned out to be from a slightly damaged gasket during previous work. While the part itself was not expensive, accessing the exhaust temperature sensor required significant labor time. A few additional signs that confirmed my diagnosis: Engine running in reduced power mode to protect components, Fluctuating engine performance depending on temperature, Consistent check engine light without other warning indicators Given the matching symptoms and similar engine configuration between our cars, I strongly suspect your exhaust component issues mirror mine. The engine management system is quite sensitive to exhaust sensor readings, which explains the immediate performance impact. My suggestion would be to proceed with a full diagnostic at a qualified workshop, focusing specifically on the exhaust system and temperature sensor setup.

Thanks for the detailed follow-up information. The exhaust temperature sensor problem has gotten worse since my last post. During my morning commute, the power loss became even more severe, and fuel consumption has increased further. The quick look from the mechanic helped confirm my suspicions about the sensor readings being off, but given the rapid deterioration, I will schedule a complete diagnostic scan right away. It is reassuring to hear that your repair process resulted in a full resolution of similar symptoms. Based on your experience with heat sensor replacement and the thorough diagnostic steps your workshop took, I feel more confident about proceeding with repairs. The 265 Euro cost seems reasonable for the sensor replacement and associated labor, considering the detailed inspection of surrounding exhaust components. Will book an appointment tomorrow to have them run the complete diagnostic scan and check for any potential leaks in the exhaust system. Since no additional warning lights have appeared and the symptoms match your case so closely, I am hopeful this will resolve the engine management issues I am experiencing.