Ok, so I think the problem was the DPF pressure sensor pipes.
I changed them today (and changed the oil and oil filter whilst I was at it). Hooked up VIDA to reset the service reminder indicator and the DPF blocked fault was gone.
With the new pressure sensor pipes I got the following pressure readings:
3hPa @ 788 rpm,
8hPa @ 2000 rpm,
16hPa @ 2500 rpm, and
29hPa @ 2900 rpm.
Turned the ignition off and back on again and sure enough no DPF blocked fault.
I took the car for a quick spin on the dual carriage way with someone keeping an eye on the DPF temperature and pressure sensor readings.
The pressure got quite high a couple of times (max. 127hPa) but then the DPF temperature got up to 550C + a few times and the pressure reduced down to aroun 47 hPa at around 2.5-3k rpm. So in other words it looked like it regened a couple of times whilst out on the road.
So basically I think the pressure pipes were at fault giving the super high pressure differential readings, which also stopped the car regening itself. Changing the pipes gave pressure readings in the noral range for the car to regen itself.
However, I'm slightly suspicious that there may be something causing the soot levels to build up quicker than normal and leading the car to regen itself more often than it should (hence the build up of diesel in the engine oil - there was around 1 litre more than I put in at the last service).
So, while I think I have solved the imediate problem, any suggestions on other things to check to make sure I don't have a soot build up probelm would be much appreciated. I think I've seen threads talking about blocked up EGR valve and/or dirty injectors leading to soot build up.
I'll post an update, for reference, if anything changes or if I find out any more.
Cheers,
Wil
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