C5 Central locking

[PC2CV]

I got the lend of a sealey key fob tester to see if my C5s key fob was working and it does seem to be, but i cant get it to unlock or lock the car.
This is after holding down the lock button while turning the key in the ignition. Is there any other things that have to be checked for the central locking to work?

[GiveMeABreak]

Not sure if I've read you're post correctly, but as you have written it, you don't hold the lock button down whilst turning the key in the ignition. You pt the key in the ignition, turn the ignition on, then hold down the lock button for about 10 seconds. This just resynchronises the keys and is usually also done after a BSI reset. When did you last change the fob battery? For the price of a battery - might be worth replacing it and then re-synching as described above.

[PC2CV]

Ah thanks for that, that got it working again.