Open drivers door and alarm sound starts, stopping when door closed

Also I apologize in advance for the following questions being for another unrelated topic.

I have been noticing that sometimes after unlocking the car I open the driver side door and an alarm like sound starts, stopping when I close the door. This behaviour is not constant and never happens for another door. Any idea of what it is? I might record it if necessary.

Another thing is the other day my remote control was not responding and I couldn't enter the car. After some messing around with the keyhole (which was not turning), I managed to turn it and I unlocked the car, which, at the same time, made the remote control work again. Does it sound like a faulty central locking system or the key battery being low?

Finally, I noticed that after the car locks the doors when driving, people still manage to open the door from the outside even tho the central locking button is solid red. Important to note that when I exit the car and lock it with the remote, it actually locks all doors and trunk.

Thank you for all the help so far!

Edit: related to the main post, I don't have the factory radio installed (which in turn has a problem of not turning on with the ignition, but that is topic for another time)

Hi

This is not a common thing for the C3 to do. Mine doesn't.

Does yours have an alarm fitted?

A recording can be uploaded to youtube and linked here so we can hear the sound too.

Pimonteiro wrote: ↑Wed Mar 01, 2023 1:23 pm Edit: related to the main post, I don't have the factory radio installed (which in turn has a problem of not turning on with the ignition, but that is topic for another time)

Oops!! If the stock radio is physically removed from a pre-facelift (CAN-VAN) car and the BSI is not "told" about it, that WILL screw up the central locking. The old stock radio needs to be re-installed OR you need to use a LEXIA scan tool to tell the car it doesn't have a radio (even if it actually does).

Pimonteiro wrote: ↑Wed Mar 01, 2023 1:23 pm I have been noticing that sometimes after unlocking the car I open the driver side door and an alarm like sound starts, stopping when I close the door. This behaviour is not constant and never happens for another door. Any idea of what it is? I might record it if necessary.

If it's 3 high pitched beeps in quick succession, a pause, repeat, then the car "thinks" that the ignition key is still in the ignition. The switch in the ignition barrel which detects that the key is in the ignition might be "sticking".