well, on the saxo there is an interior light mounted on the roof, remove this with a flat bladed screwdriver and the wire and central locking senor is be visible, remove this and leave them and to dry and reconnect, you could remove and roof mast and wipe any any damp that has occured, once done reconnect the test your locking system, note; this may have to be left for a day or 2 to dry out.
Any problems please let me know
Regards
Andy, February 2008