Thalia exhaust leak

Sounds familiar! I had similar symptoms with my Thalia. Check engine light, sluggish acceleration, and drinking fuel like crazy. The exhaust temperature sensor was indeed the culprit, but the underlying cause was a small leak in the exhaust system itself.

A leak? So, the sensor wasn't actually faulty, but the readings were off because of the leak messing with the exhaust gases? How did you pinpoint the leak? Did it make a racket?

Exactly! The sensor was doing its job, reporting the wrong temperature, but the reason was the leak. I didn't spot it myself; I took it to a workshop, and they used a smoke test to find a tiny crack near one of the joints. Honestly, it was so small I never would have found it. Best to get it checked professionally. I drove too long like that. It might even damage the catalytic converter in the long run.

Okay, you've convinced me. A workshop visit it is! It's better to pay 265€ now than to risk ruining the whole exhaust system later. Thanks a lot for the advice! Turns out the repair was exactly what you described: exhaust system leak, faulty readings from the temperature sensor, and the whole thing had to be replaced. Now she runs like new!