Sounds like it could be the G201 pressure sender fault 01435, was common around that era of VAG models, there is a VAG oem repair kit out now (when i had the fault there wasn't such a repair kit and it was either a new ECU at £1500 or a recon one at about £600 fitted) The repair kit is about £150 now i think. Sure someone else will be along soon with some more info, it might not be that though!