This car had been to other garages before me and had £600 spent on it and no further forward, in fact the car was losing more power every day.
My Diagnosis
Initially I scanned for faults and found a fault for differential pressure sensor which is what monitors the dpf pressure and calculates the soot content. so I checked the pressure and found it to be 960 mbar at idle which is severely blocked, I preceded with a Terraclean Dpf clean and afterwards the back pressure was 60 mbar at idle my eventual target is below 10 mbar, my next step was to establish the reason the dpf became blocked, I then identified poor boost performance from the turbo which one garage had told the owner it needed replacing, so I set about with further tests to confirm this but I identified a blocked vacuum pipe which was stopping the turbo being activated.
The Repair to original cause
I cleared the vacuum blockage and normal service resumed, I then drove the car and the car did a successful regeneration with no further issues. If I had been contacted when the problem first started this would have been a very inexpensive repair