The car returned after about 300 miles of running ok but that morning it went into reduced power so it came back.
2 faults logged
DTC P242F - DPF restriction, ash accumulation above max threshold and
P2458 - DPF regeneration duration.
I could only clear P2458 so P242F remained.
I renewed the DPF temp. sensor and it now stayed at its initial 140 deg.C for a much longer time than before (as you suggested David) and then started to increase.
On road test at reduced power but still ok to drive, at between 2000-3000 rpm the temp. was 300-350 deg.C so much lower than before and the DPF pressure differential sensor was 10-26kPa which looks ok to me.
I am assuming that because a DTC is logged it will not do a regen either driving or forced, is this correct?
Is it worth trying to reset the DPF as though it has been replaced,hopefully I can then clear the P242F and then driving to see if it will do a regen?
Can I tell from live data whilst driving if it is actually doing the regen?
Thanks for your help, Martin.