Peugeot Partner exhaust temperature sensor issue

That sounds eerily familiar! I had a similar experience with my old Saab 9-3. Check engine light, sluggish performance, and the fuel consumption went through the roof! In my case, it turned out to be a faulty exhaust temperature sensor, too. The sensor was sending incorrect readings to the engine management system, which then messed with the fuel-air mixture and timing. It's like your car's brain is getting false information and making bad decisions. Did you check the exhaust pipe and its connections?

How did you pinpoint the exhaust temperature sensor as the problem? And how did you fix it in the end?

Well, in my case, the mechanic used an OBD scanner to read the error codes. It pointed directly to the exhaust temperature sensor. He then checked the sensor's wiring and the sensor itself. Although the scanner may help you, you still should check the exhaust pipe, since that was what caused the faulty sensor. Because of the leak, the sensor stopped working correctly. I suggest taking your Peugeot to a trusted workshop to get it properly diagnosed and repaired. It will be better than trying to fix it yourself, and you will be able to get your car back on the road as soon as possible.

Thanks a lot for the advice! I took it to the workshop, and it was indeed the exhaust temperature sensor, likely caused by a small exhaust leak. They replaced the sensor and fixed the leak. Cost me 265€, but at least it's running smoothly again!