Security fault
 

'08 Cayman. Auto door locks double click, lock/unlock, every time I drive away and the horn beeps twice. For now I have the fuse out and the horn unplugged. Is there likely cause ? How much $$$$ to get it fixed ? Thanks.

You have an open switch in the alarm system. By far, the easiest way to find it is to scan the car with a Porsche specific scan tool, which can read the last ten alarm faults stored in memory, which will point you to the problem.

Can someone recomend a particular scan tool please ?

Durametric (cable, s/w, runs on windows laptop), PST2, PIWIS (the letter two most common at P-car dealerships. A few Independents have PST2s)

I got a code for driver seat belt resistance out of spec. Any clue if this is related or what to do about it ?

Just bringing this back to say it is fixed. Door harness was pinched flat. One small bare spot on one wire grounding out. Thanks to the body shop that painted the door.