The engine immobiliser is armed automatically a short time after you have switched the ignition off.
The indicator in the instrument cluster will flash to confirm that the system is operating.
Ford Focus Welding Precautions - Steel - Description and Operation
Material
Item
Specification
Motorcraft Premium Undercoating PM-25-A (or equivalent)
—
Motorcraft Rust Inhibitor Aerosol PM-24-A (or equivalent)
—
General Equipment
3 Phase In ...