When I scanned the car to suss out the boost limitting I got a code 17978 (I think) saying the immobiliser had prevented the starting. Leaving work on Thursday it kept starting then cutting out straight away but once fired it was fine. Today it wouldn't start and the immob light kept flashing. When it did finally start the immob light stayed flashing all the way home and is flashing on subsequent start ups.
Any ideas folks as I'm really starting to think with 165k on the clocks it might be time to break it up and buy something else.