OK, about a week ago whilst I'd been driving for around an hour up the m40 my car lost boost, it came back a couple times but then went again and now its gone all the time. I can hear the turbo spooling a tiny bit but cant feel anything

code reader says boost pressure limit exceeded and if I clear the code it comes straight back again. I've checked all hoses and no blockages or anything like that. anyone have any ideas what it could be?

engines an AUM its a mk3 conversion with all the usual n249 n112 sai deletes and a catch can installed, also running a spots cat if that makes any difference