BMW 7 Diesel DPF Problems: Power Loss and Heavy Smoke

Hey there! I have some experience working on cars and went through something very similar with my 2005 BMW 5 series diesel. Also own a 3 series from that generation. The symptoms you describe match exactly what I experienced, DPF light, drop in power, smoke issues. It turned out my exhaust back pressure sensor was shot. Had it diagnosed and fixed at my regular workshop, cost me about 245 Euro total. The repair brought everything back to normal. Before I share more specific details that might help, could you share: Current mileage on your car? Any other warning lights? How long has this been happening? Have you had any recent DPF regeneration cycles? Let me know these details and I can give you more targeted advice based on my experience.

Thanks for the detailed reply! My 7 has 67669 KM on it and just had its service last month. No other warning lights showing up right now. The issues started about a week ago, and I haven't noticed any active regeneration cycles lately. The symptoms seem to match what you experienced with your 5 series. I'll definitely look into the back pressure sensor, that's a much better scenario than having to replace the entire DPF. Did you notice any specific driving patterns that made the symptoms worse before you got it fixed?

Hey again! Thanks for the additional details about your 7 series. Yeah, looking at what you've described, it's even more convinced that we're dealing with the same issue I had on my 5 series. Before I got mine fixed, I definitely noticed the symptoms got way worse during city driving and short trips. The smoke and power loss were particularly bad when the engine was cold or during stop-and-go traffic. My mechanic explained that these conditions prevent proper DPF regeneration, which makes sense. With my 5 series, I initially thought I needed a whole new DPF unit (which would've cost a fortune!), but the faulty pressure sensor was the real culprit. After the sensor replacement, all the symptoms cleared up within a couple of days of normal driving. Given your mileage is relatively low and you've kept up with services, I'd bet money you're dealing with the same sensor issue. One tip though, while you're getting it checked out, have them look at the sensor wiring too. On my car, there was some minor wire damage that needed fixing as well. Tell you what, when you get it looked at, let me know what they find. I'm really curious if it turns out to be the same problem. These BMWs from that era seem to share quite a few common issues!

Thanks so much for sharing your experience and the extra details! It's really helpful to hear from someone who's been through the same thing. I've scheduled an appointment with my mechanic for tomorrow morning and specifically asked them to check the pressure sensor and wiring based on your advice. You've definitely saved me some stress, I was worried I'd be looking at a complete DPF replacement! I've actually noticed the same pattern you mentioned with the city driving making things worse. I'll try to stick to longer drives until it's fixed. The price you mentioned for the repair sounds way more manageable than what I was fearing. Really appreciate you taking the time to help me out here. Will update you once I get the diagnosis, fingers crossed it's just the sensor like in your case!