If you have, or can get access to nanocom / test book , under bcu settings , set to always disarm with key , this is good practice even if you have 2 working fobs, you can then disarm the immobiliser when you unlock the door with key only , there are only 2 frequency's, to around sep 1999 is 315 MHz , after that 433 MHz unless U.S which was 315 , right through, handy to know if you buy a replacement fob

