have you replaced this part http://cgi.ebay.co.uk/MK3-GOLF-CORRADO-VR6-READER-COIL-VENTO-PASSAT-/200411614802?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2ea9768e52 the standard immobiliser is in the key and reacts with this part inside the ignition cowling just unplugs under the dash