Gregers, I have to agree, the only thing to have happened was the transponder chip went "missing" out of the key fob for a few days. Nothing else has changed. I had a thought that since we used the key many times, the PATS may be out of sync with the transponder chip. As far as i know, the PATS transmits a rolling code to the transponder. The other thought I had, which is pure theory, is if the car sees many key turns without a transponder, it might think the car is trying to be broken into and immobilise itself. Do you have idea how to fix the problem? Any clues will be much appriciated Thanks