Ty for the reply vaughant but its not the cat as i have loads of pressure at the back box as i thought the same but clear the code and its mint again for a few miles. I think its the lamba sensor playing up as when i go into live data its not switching much at all.

Just dont want to buy one to find the code is for something different and chucked more money away. The thing that gets me is why the hell dont vw use the same codes for stuff as other car makers