Central locking D3

[Dirty3]

Noticed on two recent occasions that the cars alarm went of (horn beeping) about 5-10 minutes after locking. Unlocked car, checked all doors/windows secure. Now the lights don't flash three times when door locks, but I get an udible horn blast to warn me a door is left open, but its not.

Any ideas. I'm going to try the spare key incase the other is getting low battery but it doesn't seem right.

Cheers,
Neil.

[jonesy63]

Did you check the bonnet latch sensor is clean/working?

[Dirty3]

Did you check the bonnet latch sensor is clean/working?

Yep, did that too.
Funny enough I tried the spare key. It appears that maybe the key i was using may have a battery about to go. The spare opens and closes no issue and no horn blast upon closing, also the lights flash three times as they should but with usual key it stopped doing this at the time it started to play up.