Alarm

[Keith lewis]

Car alarm going off on its own when I lock it 

[Steve Q]

I'd recommend a diagnostic check to see if any fault codes flag up. But could be as simple as a fly! 

Might be worth getting the battery tested especially if it's over 5 years old. 

[FMOB]

Do check for any DTC's to see if there any dodgy sensors, if none are shown it could be the siren battery backup failing, the siren isn't intelligent and diagnosis is usually by swapping with a known good one or just replacing batteries in the old one.

If the siren is as I remember, you need to cut it open to get to the batteries so not an easy DIY job.

Just my 10c's worth.