Peugeot 406 Reduced Engine Power

I also have a 406, and had something similar happen a while back. Does it feel like the car is struggling to accelerate, especially uphill? Was any work done on the car's computer recently, like a chip tune or anything?

Yeah, it's exactly as you described. It struggles on hills big time. As for the chip tuning, I am unsure, since I bought the car used a couple of years ago. Is that a possible cause?

It's definitely a possibility. After some research, I found that a faulty chip tuning by third-party providers often messes with the engine's computer and throws up errors, triggering limp mode. I'd recommend having it checked out by a professional workshop. They can diagnose the car properly.

Thanks for the tip! Took it to a workshop, and you were right - some aftermarket chip tuning was causing the issue. They reset it and everything's running smoothly now. Cost me 180€, but worth it to have the car running normally again.