Hiya i just joined the forum ive brought a mondeo gia x the fob needs the battery replacing if i change it will it lose its coding any help would be great

First of all welcome lo the forum.
I hope you enjoy your stay.
The key may lose it's central locking coding but can be reprogrammed in about a minute.
Search the web for 'Mirez' and look for the key coding instructions.
The immobiliser part of the key does not require battery power to work so will be unaffected.