How do you know the DPF needs replacing/cleaning?
 

I know that there is a mileage remaining value that comes from the DDE but I suspect the previous owner did a DPF reset in an effort to solve a DPF-related issue.

My X5 has 140k miles on the clock so it is about time but I'd like to know for sure... so the question is what measures or signs tell you that it is end of life?

Soot at your tail pipes is a good indicator from what I've read. Ours is at 166000 and is still doing it's job. I have the DPF off right now doing a trans swap (what a PITA to get it out), haven't looked into having it cleaned. Any info on who offers this service? I doubt it's a DIY type of service.

The car apparently has a flag that sets around 130,000 miles but the true measure would be the differential pressure across the DPF which the car has a sensor for and can be monitored with INPA or ISTA (possible other readers as well).

My differential pressure is erratic - about 90% of the time it is high and regens happen every 30 miles or so. I suspected the DPF pressure sensor and changed it but it could just be the DPF is clogged. Just a bit concerned why sometimes the readings are ok...