[einsteiger]

I am not a Porsche owner, so this is coming from my associations with others like yourself and reading innumerable threads on related subjects. If the sensor replacement does not work, could the ignition switch be the culprit? The intermittent nature you discussed seems to be a common element in all of the "it was the 8#$%*! ignition switch" threads I've gone through. If you already have a new switch, then never mind.

Good luck. I have a hunch you will track it down in no time.