SQ7 Power Loss Due to Faulty Exhaust Temp Sensor

I had a similar issue with a 2018 S7 4.0 TFSI last year. As someone with moderate experience working on Audis, I initially thought it was just a sensor malfunction. The exhaust sensor was indeed the culprit, but the root cause was actually a small leak in the exhaust system that affected the temperature sensor readings. The engine management system was getting incorrect data, forcing the car into limp mode as a safety measure. The repair involved: Complete diagnostic scan, Replacement of the faulty heat sensor, Repair of the exhaust component where the leak occurred, System reset and testing Total cost was 265 Euro for parts and labor. The car has been running perfectly since, with normal power delivery and fuel consumption restored. Before jumping to conclusions about your SQ7, could you share: Are you getting any specific error codes? Did you notice any unusual sounds from the exhaust system? When exactly did the temperature sensor warning first appear? Have you noticed any exhaust smell in the cabin? This information would help determine if your issue matches what I experienced with my S7.

For those interested, I just had my car serviced at 185142 KM. The engine management system diagnostic revealed it was indeed a faulty exhaust temperature sensor causing the power loss. The car exhaust was thoroughly inspected and no leaks were found. The heat sensor replacement fixed the issue completely. Total repair cost was 390 Euro including labor. Power delivery is now back to normal and fuel consumption has improved significantly. The mechanic mentioned these sensors commonly fail on high-performance engines around this mileage point. Worth checking for anyone experiencing similar symptoms.

Thanks for the update on your SQ7 repair. Interesting that your case ended up being just the temperature sensor, exactly what happened with my S7 initially, though mine had the added exhaust leak complication. The price difference between our repairs (390 Euro vs 265 Euro) makes sense since yours is a newer model with updated emission control components. These newer sensors tend to cost more but are generally more reliable once replaced. Good to hear the engine management system is working properly again. The power restoration and improved fuel consumption matches my experience after the repair. My S7 has now run another 40000km without any sensor-related issues. The mechanics observation about failure rates of heat sensors in high-performance engines aligns with what I learned during my repair. The extreme temperature variations these sensors endure, especially in turbocharged engines like ours, can definitely lead to earlier wear. Have you noticed any other improvements since the repair, particularly in cold-start behavior or engine smoothness?

Going well after the repair, I appreciate everyones input. The car starts perfectly now and runs smoother overall, especially during cold starts. The engine management system is working as intended with no more warning lights. For anyone searching with similar issues, make sure to get a proper diagnostic scan of the exhaust sensor system. While my problem was a straightforward temperature sensor replacement, others have found additional exhaust component issues that needed addressing. The 390 Euro repair cost was reasonable considering the complexity of these high-performance engines and their emission control systems. Regular maintenance and prompt attention to warning lights helped prevent any cascade failures that could have been much more expensive. The car has now done 1000km since the repair with perfect performance and normal fuel consumption. Based on what the mechanic said about typical sensor lifespan, I will likely budget for another replacement around 300000km as preventive maintenance.