BMW 8 DPF System Failure: Black Smoke and Poor Power

Hey there! I had almost identical issues with my 2020 BMW 7 Series diesel last winter. The symptoms you're describing match what I experienced, DPF warning, sluggish performance, and black smoke. After a diagnostic scan, it turned out the exhaust back pressure sensor was failing to send correct readings to the ECU. This prevented proper DPF regeneration cycles. The sensor was completely clogged with carbon deposits. The repair involved replacing the back pressure sensor and cleaning the DPF system. It was a serious job since a faulty sensor can lead to complete DPF failure if left unfixed. The mechanic also performed a forced DPF regeneration after the sensor replacement. My advice: Get it checked by a BMW specialist who knows diesel systems well. Make sure they do a proper diagnostic scan first. Don't drive it too long with these symptoms, as it could damage your DPF permanently. Hope this helps with your decision.

Thanks a lot for sharing your experience, Dave! This definitely sounds exactly like my problem. The symptoms match perfectly, and it's good to know I'm likely on the right track with the pressure sensor theory. Quick question, do you remember roughly how much you ended up paying for the whole repair job? Also, has everything been running smoothly since the fix, or have you noticed any other issues pop up? Thanks again for the detailed explanation. Really appreciate it!

Good news, I got the issue sorted! After my last post, I took it to a BMW specialist and you'll be glad to know I was spot on about the exhaust back pressure sensor. They replaced it and the total cost came to 245 €, quite reasonable considering the potential nightmare of a full DPF replacement. The car's been running like a dream since the fix, no more black smoke, performance is back to normal, and the DPF warning light hasn't shown its face again. The regeneration cycles are working perfectly now. It's amazing what one faulty sensor can do to these modern diesels! Just make sure you get a proper specialist to do the work, they'll know exactly what they're looking at. Trust me, it's worth every penny to get it done right. These symptoms can spiral into bigger problems if left unchecked. Let me know how you get on with yours!

Thanks Dave, you're an absolute lifesaver! I actually just got back from the mechanic today. You were right about everything, the exhaust back pressure sensor was the culprit. Funny enough, my repair cost was pretty similar to yours. The best part? The car's running perfectly now. No more black smoke, the warning light's gone, and it's got that smooth power delivery back. Such a relief it wasn't anything more serious! The mechanic did mention I was smart to bring it in quickly before it could cause any damage to the DPF itself. Really grateful for your advice about going to a specialist. The guy I found really knew his stuff and fixed it right the first time, unlike my previous mechanic who just kept scratching his head at the problem. Thanks again for pointing me in the right direction. It saved me a lot of time and potentially a lot more money!