Thanks to all for the knowledge being passed on here and as well as helping me right now I also hope it proves useful to other owners in the the future.
It’s reassuring to know that the crack in the pipe probably explains the “full” DPF, and it’s not surprising that in 185,000 miles some sensors have worn out. For all I know the DPF pressure sensor could have been out for some time, just with the car doing mostly ‘good’ long journeys the soot build up associated with low speed, short trips never got a chance to accumulate. Either way, I’m happy this will be sorted.
On the topic of tackling jobs to avoid bills, it sounds great in theory but assumes a) mechanical ability and b) time. I’m lacking in both unfortunately.
With the benefit of hindsight and the knowledge of an accurate diagnosis of course it would be possible to source parts to limit expense, but making that diagnosis first is half the battle, not to mention then having the know-how, the tools, and the time to do something about it, all the while being essentially without transport until the work is done.
The principle of using experts to fix my car with quality parts is something I’m happy with and I accept this costs more as a consequence, and I remain extremely grateful to this forum for providing me the knowledge to ‘keep them honest’.
Anyway, wish me (and my wallet) luck for Monday.
