You take a higher end OBD tool (hint: not the kind you'd buy at Auto Zone), access the keyless entry module, and select "invalidate all fobs" from the menu. Once that procedure is done, any key fob the vehicle is set up will be forgotten, and you can program the module to accept a new key fob.
what is the reason for not fixing camera in key fob
Free On Board (FOB)
A key fob is for instance a mini card on your keyring, for instance I have a tesco's clubcard key fob on my keyring therefore when I put petrol in my car and pay at the checkout instead of finding my clubcard I get my key fob!
C200 key fob problem
By driving with the key fob in the ignition.
You do not have to reset the key fob when changing the battery.
there is a terminal block under bonnet on right hand side attach battery charger to it until key fob works
how do i reset key fob for a vw golf 2001 how do i reset key fob for a vw golf 2001
The key fob doesn't get reset... the keyless entry module gets programmed to accept commands from that key fob. If your key fob suddenly stops working and it's not a battery issue, then you either have a problem with your key fob itself, or the keyless entry module, and it'll need to be diagnosed and repaired accordingly.
Not sure what fob is! But for the key, you need to approach the Mercedes Benz dealership. For the C240, 2002 model, I had to pay around $250 for a new key. It can open and close the door from around a block, so take care that you don't accidently open your car while handling your keys!
on the key fob, turn the key over so that the buttons are on the back. there is a small groove near the blade/key end of the fob. you can prise this open using a small screwdriver or if you're strong pull the blade/key part outward/away from the fob. the remaining key fob can then be split in two to get at the battery. beware that you only have a very short time to replace the battery or the fob will go out of sync with the car.
To add a new key fob, take the vehicle and the key fob to an authorized dealer. To re-program a key fob after replacing it's battery, open the key fob, then read and follow the instructions inside.