sounds like yr alarm is picking up a fault, like it has activated, just bypass it with the switch under the bonnet by the bulkhead, lets face it no one will nick a xantia, yr immob keypad will still work, had this prob on several of my xantia, alarms arent brill on these, also worth checking all door/bonnet/boot/tailgate switches etc, unusal cases of water in remote sensor just above rear view mirror if sunroof fitted,
bx owner
February 2010