XR4Tim

I have had a bad ignition switch cause this problem on a 993.

henkinc

turns out the code showed hood latch open, which it was not, but the jack had been leaning on and sort of stretching the cable carrying the latch signal to the car. Reset jack correctly, checked contacts on cable and hope it does not recur. Ignition switch checked out fine.

henkinc

well, the horn went off again after about 6 hours. The next suspicious code was the interior light/movement sensor, integrated in a single light above the rear view mirror in the cab. I pulled the fuse for this and will see if this prevents the alarm from going off.

henkinc

UPdate - car alarm does NOT go off when car is unlocked. It also does not go off when the fuse #29 (for interior light and Infra rad movement sesor) is removed. Porshce dealer read codes and movement sensor triggered the last 7 of 10 alarms. Hence, faulty interioir light device must be culprit.

Anyone else have a failing interior light system??

Charlie