My car was due for a service and the DPF light started flashing. My car was booked in at an independant garage, but was not due for a few days. As the service was due 500 miles previously, I suspected that the flashing DPF light is also used as a service indicator. I checked the oil level and it was nowhere near the X mark. I remembered having filed away details of how to manually reset the ECU and decided to try it out.
Basically, it's earthing out this pin socket
and doing the following.
Before connecting the wire, turn ON the ignition.
Connect the pin socket to earth (I used the battery earth as it's so near).
Press the accelerator to the floor and release 5 times
Ignition OFF and disconnect.
The first time I did this, nothing happened, but after a couple more tries, I found that the accelerator had to be depressed and released rapidly. The glowplug warning light flashed briefley and the DPF light vanished. After switching off and disconnecting the wire, on restarting the car, I was pleased to see that the DPF light went out as usual.
I've driven the car for a couple of hundred miles since and all seems to be well and hopefully will be until it is serviced.