Re: Weird Alarm Noise
Not sure if it's the same as yours, but my 156 does this second beep too at odd times, only real downside means I have to disable the alarm before opening the boot if the car is locked or annoy the neighbours if i forget. For me it only ever happens after heavy rain and ONLY if i've opened the bonnet!
If i waited for a couple of days (presumably until the micro switch on the bonnet beside the catch has dried out) then open boot/bonnet/doors, close them all (seems to reset the alarm?) and then lock the car the second beep disappears. Now i just ignore it and it goes away after 2/3 days.
It's been checked by the indi, for security purposes, but it seems everything works otherwise and to fix it seems to be a case of replacing micro switches one by one until the fault goes away but they don't consider it a real issue. Bonnet microswitch is easy enough to replace, but by the time you get to all of the switches and labour rates it's starting to look expensive for something that isn't really much of a problem, especially as it goes away by itself after a couple of dry days. I'm just trying to make myself remember Not to open the bonnet after heavy rain!
Probably spraying the switches with WD40 would get rid of the water, but I'd be more concerned about this holding onto dust etc. and making the problem worse than the occasional extra beep!
Hope this helps.