Hmmm, just came back to bite me this one!

The DPF has again blocked up. After some head scratching, many cups of tea and an 'epiphany' in the middle of the night i decided to check the coolant temp with diagnostics (no engine temp gauge in the E60).

Sure enough, the engine was constantly running cold (~65 degrees)which was causing the engine to over-fuel and clog the DPF. As the coolant never gets to 75 degrees, which is one of the pre-conditions for a regeneration, it never regenerated and therfore just blocked up again!

So, two new thermostats later (a main stat and an EGR stat - they were both goosed!) and the coolant is now a nice steady 92 degrees. However, the DPF is still throwing a "DPF blocked" code after cleaning and the car doesnt want to do a regen, even if i force it through diagnostics.

Looks like we are going to need a new DPF on this one!