Ford Focus Program the independent remote key to replace the integrated key head remote transmitter
Beginning around 2007, Ford started moving from use of stand-alone keys and remote fobs to use of an integrated part with the remote transmitter functions in the key head. In doing so, they did not change the transmitter technology for many years thereafter. So, stand-alone remotes can be used to replace the transmitter functions of a Ford keyhead part through 2014 or so.
In addition to the keyless entry transmitter technology, an integrated keyhead part has a transponder in it that interacts with the anti-theft system in the steering column. To use either a new integrated keyhead part or a stand-alone remote with one of these Ford vehicles, systems in the vehicle have to be programmed to accept the new part.
Programming a vehicle oneself to accept the anti-theft transponder in a new keyhead part involves a procedure that requires two distinct keys that already work for the vehicle. This programming procedure also supports programming of the transmitter functions.
If one is adding a stand-alone key fob remote only, a second procedure that only requires one key can be used.