Horn Sounds Twice when unlocking

Hi, I have a 1999 996 C2 and it has developed a feature, when i unlock her via the key fob the horn sounds twice, i took her into the main dealer who replaced the battery, but the new feature is still there, in fact i now have the red light showing on the dash which usually indicates that the dead locks have been activated, but they haven't? Any ideas please?

Quotes source post: 7410866

My 02 Boxster does this and has the same symptom every once in a while. It has been since last fall when this last occurred until the other day when it happened again out of the blue. The door lock button's LED comes on sometimes after a few moments after getting the car moving. If I press the unlock side of the button the LED goes off but can come back on again for no apparent reason. Eventually as I drive the LED remains off and the car has not done this again for several unlocks/drives/locks events. My car's battery ok -- not even 2 years old -- and there's no dampness to be found anywhere with the carpets. (I keep the drains under the front cowl covers and under the clamshell clear of debris so any water can drain through without any problems.) Checked the owners manual and it advises if the alarm horn sounds when locking or unlocking the car or if the door lock LED comes on or flashes to have the car seen by a Porsche service department for diagnosis. One of these days... My WAG is some electrical connection to the security system controller is marginal, probably due to age and normal surface corrosion. When the controller fails to get the necessary sensor input signal it sounds the alarm and does the LED thing. Sincerely, Macster.

Usually this indicates that there is a fault, typically something like the console, trunk or engine lid is not completely closed. Check these and the doors and see if that clears up the problem.

I think we've had a thread already about beeping on door lock/unlock. As a result of that thread I had a dealer check out why I get the horn doing a single beep when locking the car as everyone told me here it was because it was a fault or something open. Found out that it was programmed by someone in the car's past (we think in Vegas) and has to be done on the factory test unit and is not user programmable. The tech told me there are a few other things that can be programmed that people are mostly unaware that can be done depending on models of P cars and years.

I think it will do that if you unlock before the sytem has compleely armed which probably looks the same to the computer as a fault condition. Is the system fully armed and a steady spaced flash of the light on the dash when armed? If its like 2 flashes together then something errored on arming.