This process explains how to turn off the alarm if it goes off on your Porsche 993 in case your remote set is malfunctioning or you do not have any. This little trick will work on most 993’s if the feature is programmed on their computer. To disable the alarm: 

Once the alarm goes off due to an error or problem, simply put the key in the driver's side door, turn it to the left and hold it there for a few seconds. The alarm will hopefully turn off.