My D3 is about 175k miles now and as far as I know on original DPFs. A while ago glow lug light came on and there was an error regarding DPF pressure sensor, no effect on performance. I cleared, gave it some beans and it's been fine for about 4 months, error not coming back. I know previous owner replaced a sensor or 2 but there is 4 of them. They are not that expensive but located above gearbox so to access you need to drop subframe with gearbox/engine.
Then couple of days ago I joined dual carriage way full throttle - glow plug light came on again and lost power and max 2.5k rpm. I had to embarrassingly after overtaking everyone pull back in first lane and let everybody by
Cycling ignition did not help. This time it came up with DPF efficiency threshold error. Clearing error restored power but going full throttle would bring error and limp mode back. I checked soot values and they were 18-19g calculated and 14-15g measured which is well within limits. I assume because soot is low ECU does not start regen but DPF is partially blocked by ash which does not burn off during regen or maybe oil residue or something, or pressure sensors give wrong readings so at full throttle with a lot of gasses trying to flow through DPFs there is too much pressure differential and it throws fault code.
Anyway did forced regen and then some 20 mile drive in 4th gear, this brought soot level down to 8g calculated, 4g measured, then raised back to 8-9g both calculated and measured. It now works fine and and does not go in limp mode even at full throttle but I think the DPF days are numbered.
So I am thinking DPF removal and remap is in order. Can anyone recommend a place in Midlands, preferably with dyno as well. I see MRC did 2007 Q7 4.2TDI remap about half year ago and got 416PS 957Nm( does not mention anything about DPF) which is quite impressive considering most tuning places only say 375PS. Not sure what it cost but I guess MRC are not cheap.
Depending what the cost difference is I might gut the DPFs myself and just go for remap but would prefer it all to be done by someone else.