Ford Focus Owners Manual: Principle of operation

Engine immobiliser

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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 Compass Calibration
NOTE: For optimum calibration, drive to an open, level location away from large metallic objects or structures such as bridges, steel buildings, etc. Switch off all non-essential electrical accessories (heated rear window, heater fan, A/C, map lamps, and wipers) and make sure all doors a ...