Geoffers,
Firstly it's a 2005 GS300 not 1995 (I'm a plonker). The sensor connected and is damaged - scraped and remains on if reverse is selected. If you push it in it stops bleeping but the moment you release it it beeps.The guy who is repairing the bumper thinks only possibilty is to buy the lexus part (£145) as these are factory fitted I did wonder if it could be left disconnected but cant find out until bumper is off which doesnt leave enough time to get part and I dont suppose lexus would reimburse me if we didnt use the part. hope this now make some sense