Ford Focus Owners Manual: Principle of operation

Engine immobiliser

...

Coded keys

Note: Do not shield your keys with metal objects. This may prevent the receiver from recognising your key as a valid one. Note: Have all of your remaining keys erased and recoded if you lose a key ...

More about Ford Focus:

Ford Focus Front Disc Brake
The front brake disc system consists of the following components: Brake caliper anchor plate Brake caliper Brake disc Brake flexible hose When mechanical force is applied by the driver to the brake pedal, the force is converted into hydraulic pressure by the master cylinder. The ...