Central locking not locking

Hi,

During the last couple of days I've noticed that when I leave the car (A4 1.9TDI 2003) and try to lock it with the remote fob, nothing happens. The only way to remedy it seems to be switching on the ignition again (not engine), then off again. Then it seems to work (have I by chance re-synched it by doing this?). Any ideas what's causing this? Dodgy door contacts? The fob (+spare) were resynched a couple of months ago. My other theory is the mobile. It says in the manual that it can interfere with the central locking. I tend to have it placed in the pocket near the handbrake. Of course now I'm using a hands-free earphone thingy which might make the problem worse because of the wire properties!
I'm looking into going bluetooth but again that might interfere too.

Cheers.

sound slike it might be the fob battery ? try changing it and re-syncing again.

Will try that, thanks.

hi tony
I had the water problem caused by the polen filter lid being damaged, when the filter is changed the rear top flange on the lid is made to be flexable this can split letting water into the car.The only time you no there is water under the carpet is when you remove the trims and lift it up.The carpet itself as I see it is water proof, the rear sound proofing is foam this holds the water. Audi in there wisdom go and put the control unit that works all of the locks/windows/interior lights and more under the carpet. Big problem loads of money to fix I was quoted about £600.
The unit I replaced part No 8E0 959433 ENDING IN AL OR AJ.
If VAG-COM CANNOT TALK TO THIS UNIT IT MAY BE DAMAGED I do have a spare unit I am looking at putting on ebay soon or list here for SALE.