Hi Speedy. Good idea to stop by the forum... hopefully someone with far more exp than me had this problem before and be able to pin point it to the source for you.
It does "sound like" your gauge or the sensor is toasted but you may want to drop by your favourite Indy today and get below done on the car before starting looking anywhere else. I have a feeling, again I know crap about Porsche cars, that is you are able to calibrate it... then it is not your sensor, but the gauge itself.... etc
