My 2001 S4"s alarm keeps going off randomly in the sunlight only

[Dawn Grey]

My cars alarm seems to go off only when it's sunny and the car gets warm inside and it will go off with the car locked or unlocked , with the windows or sunroof open or closed. It goes off for about half of a minute to a minute and turns off itself to but sometimes the lights flash when the alarm goes off and sometimes not and sometimes the lights will continue to flash after the alarm goes off.
I can press the button on my keys and it will make it stop but sometimes it will go off anywhere from 3 to 8 times a day ,then other days not at all.
Does anyone have any experience with this occurring? I feel it is probably a sensor gone bad but not sure where the sensors are.
Can anyone help me??

 

[Welshquattro]

It could be the batteries in the alarm siren in the boot have final gone which is common. The siren has some non-replaceable rechargeable batteries in it that with time leak and corrode the Circuit board inside making it play up. If that's the case then you will have to replace it but if your lucky and caught it early you may be able to do a battery mod on it.

http://www.audi-sport.net/vb/showth...-Alarm-Siren-Replace-NiMH-Batteries=&p=917651

 

[s4mark]

Door microswitch bad solder joint? My s3 had this issue when the sun was beating down on the door and it would think the door was open a door set the alarm off. When it cooled down all was fine. Problem solved with a new door lock but not saying that's your issue