The Xantia is a large family car that was produced by the French automaker Citroën. Like most car manufacturers, its key fobs are by and large reliable and easy to repair. However, if you have trouble with your key fob, you can take steps to repair it by performing some simple maintenance and cleaning with simple household supplies that can be found at any local hardware store. Doing so may help you avoid purchasing a costly new Xantia key fob.
Press the blade button on the key so that the key is open. Turn your key fob over and use a Phillip's head screwdriver to loosen the screw on the underside of the key fob, opposite the key ring hole. The key fob should slip in half.
Blow the green circuit board and interior of the key fob clean with canned air. Replace the old battery with a new CR 1620 3V battery. Screw in the attachment screw and test the fob on your car. If it still does not work, proceed to Step 3.
Remove the screw from the fob and pull out the circuit board. Dip a cotton swab into rubbing alcohol and clean the contacts on the circuit board. These are the little gold squares that are underneath the keys. Allow the circuit board to dry, reassemble it and test it. If it still does not work, proceed to Step 4.
Remove the remote's interior circuit board. Older key fobs often wear off the connective metal that keeps them working properly in conjunction with the press of the button. To rebuild the contact surface, dab a tiny bit of contact paint on the contacts. Conductivity paint is available at any radio shop or hardware store. Let it dry for 12 hours before putting the fob back together and testing it.
Reassemble your key fob and test it on your car. It should be in proper working order.
In a bind, apply a bit of pencil lead to the contacts on your key fob. Simply rub the contacts with a graphite pencil to re-establish the connectivity that is needed to keep your key fob in working order.