Alarm randomly coming on

[clarke4104]

Hi just asking if anyone else has experienced this. My 2016 Avensis 1.6 diesel tourer alarm is coming on with no reason for it being activated. It’s always after I have parked up and locked the car, sometimes will come on after 10 minutes and sometimes it could be after an hour or so. I’ve found the alarm siren in the boot offside behind the furnishing panel and disconnected it however this does not solve it as when the alarm activates it sounds the car horn also and obviously for safety reasons I cannot disconnect these ( however I do disconnect at night to keep the neighbours happy) any suggestions or help would be much appreciated 

[FROSTYBALLS]

Spider or insect in car??

[clarke4104]

No did check for this, and it’s going on now for some time, tried renewing fob batteries too but no change 

[Cyker]

I have seen posts about similar problems from time to time on here, but I can't remember causes off-hand. I think one may have been a dodgy sensor, while another was maybe a wiring issue or low Battery or something?

Apparently with some models, if you lock the car with the key instead of the remote it doesn't arm the alarm.