Hi guys just an update to the post.
So as I said, on the day of the post, I took the car on an approximate 160 mile round trip. A little while before I left home, I did a few miles where it was being kept between 1500 - 3000 rpm and then just before I hit the motorway, the fault code (p2002) kicked in again. This is the first time its happened on a local drive.
I carried on to the motorway and 80 miles in stopped at my destination. I cleared the code and within an hour, was back on my return but this time, hardly used 6th gear. For the most part of the journey I was keeping it around 4000rpm to heat up the engine etc and then bringing it to around 2500 rpm to try and burn off the junk in the DPF. I repeated this process many times during the journey and the code didnt kick in whatsoever. Once I reached my destination, after a bit of local driving, the lights came back on.
Now I've just done another 80 miles on the same trip, using the same method in 5th gear and the code has not kicked it at all as of yet. I'll probably use it on some local trips tomorrow and then back on the motorway the day after but i'm thinking I'll use 6th gear this time to see what happens. Or I could carry on using 5th, cos it might potentially be working it seems, although i have no idea why or how...maybe someone could explain?