Hi, I had the same symptoms with my Opel Insignia Diesel, built in 2009. You're right, it sounds a lot like a DPF defect. In my experience at the last inspection it was exactly the same, the diesel particulate filter was internally defective. In my case, the mechanic replaced the defective DPF and recalibrated the system. This solved the problem completely and since then the car has been running perfectly, no more black clouds of smoke, no loss of power and the engine light is off. The DPF regeneration is also working regularly again. It's definitely not a minor problem, but it's also not a catastrophic defect that makes the car unusable. Hope this helps you.

(Translated from German)

Hey, thanks for the quick reply! It really sounds like what you're describing. Do you happen to remember what you had to pay for the repair and the new calibration? And has anything similar come up again since the diesel particulate filter was replaced, or has everything stayed in the green? I'm looking forward to your feedback.

(Translated from German)

Hey, no problem, always happy to help! So, I paid €1550 for the repair and recalibration of the diesel particulate filter. It was a bit expensive, but since the DPF was internally defective and then replaced, everything is really back to normal. No more black smoke and the issue with the "low remaining mileage" has also been resolved. So, no more problems since the visit to the mechanic. Hope that helps you!

(Translated from German)

Wow, that's a lot of money, but if it solves all the problems, then it's probably worth it! Your information is super helpful. I think I should also see a new mechanic to take a closer look. Thanks so much for sharing your help and experiences with me! I'll keep you guys posted.

(Translated from German)