Car alarm keeps going off.

[hewittinspain]

I have a 15 plate Leon FR. For the past two days the car alarm has gone off and it seems to be a short time after I park up at home (maybe an hour or so). This is the 3rd time it's done this in two days. Before I test the battery (I'll have to borrow a meter) is there anything else I can try?
I know for the last few days when it's been hot I've been long pressing the door unlock button so that both windows come down (due to the heat) so I don't know if anything has gone out of sync.

 

[East Yorkshire Retrofits]

A multimeter isn’t a good way of testing a battery

Global opening won’t knock anything out of sync

Check there’s nothing in front of the ultrasonic sensors near the interior light (cobwebs for example)

Check the car knows when the doors are open/closed

 

[hewittinspain]

Battery seems fine running at 12.7V going to 14 when engine on. Any ideas??

 

[East Yorkshire Retrofits]

A multimeter isn’t a good way of testing a battery