S90 exhaust back pressure sensor issue

Hey, that sounds frustrating! I had a similar issue with my 2016 Peugeot 308, although the symptoms weren't quite the same. Engine light, performance drop - the usual. Diagnostics also pointed to a faulty exhaust sensor. Did you check the sensor wiring? Maybe it's just a loose connection or corrosion?

Yeah, I gave the wiring a quick look, but didn't see anything obvious. Where was the sensor located on your Peugeot? Was it easy to access and replace? Any specific things I should look for besides the wiring?

On my Peugeot, the sensor was a pain to get to, tucked away near the DPF. But before you start tearing things apart, confirm the diagnosis. I didn't, and replaced the sensor and found that it didn't solve the issue at all. In my experience, your best bet is to take it to a workshop. They have the right tools and diagnostic gear to pinpoint the problem.

Thanks for the advice! I took it to a workshop, and you were spot on - the exhaust back pressure sensor was defective. They replaced it, and the total cost came to 245€. Runs like a charm now!