Peugeot 106 diesel particulate filter issue

Those symptoms definitely sound like they could be related to the diesel particulate filter (DPF). The reduced power and smoke point to that. A 'particulate filter' is part of the exhaust system, designed to reduce emissions. When it gets clogged or isn't working right, you get those issues. Know anyone with an OBD2 scanner who could check the exhaust back pressure sensor? A defective sensor can cause all those problems.

Thanks for the quick reply! I don't have a scanner. What exactly does the exhaust back pressure sensor do? If that's the problem, is it something I could potentially fix myself, or am I better off taking it to a shop?

The exhaust back pressure sensor measures the pressure in front of the DPF. The ECU (Engine Control Unit) uses that information to determine when to regenerate (clean) the filter. If the sensor is faulty, the ECU gets wrong info and the regeneration might not happen properly, leading to clogging and the symptoms described. While some repairs are DIY-able, dealing with the exhaust system and sensors can be tricky. I'd suggest getting it checked out by a mechanic to confirm the diagnosis. Better safe than sorry when it comes to emission control.

Thanks for the info! You were spot on. Took it to the workshop and they confirmed it was indeed the exhaust back pressure sensor. Replacing it solved all the problems. Cost me 245€ for the part and labor. Appreciate the help!