The 2003 Ford Focus headlight system is available with two options, a halogen headlight bulb and an HID headlight system. If your car has the HID system, a Ford technician must service it. If you have the halogen system in your Focus, you can replace the HB2 halogen bulb yourself. The HB2 is a common bulb and available from any auto parts store or through the Ford dealership.
Turn off the headlight switch on your Focus then open the bonnet and support it with the prop rod. Locate the bulb cover and pull it off the back of the headlight assembly.
Disconnect the electrical connector from the back of the headlight bulb and lay it aside. Locate the wire retaining clip on the back of the bulb. Unhook the end of the clip from the latch on the headlight assembly.
Swivel the retaining clip out of the way and remove the bulb from the back of the headlight assembly. Discard the old bulb and install a new HB2 bulb into the back of the assembly. Do not handle the glass portion of the headlight bulb with your hands, the oils will damage the bulb and cause it to fail.
Swivel the retaining clip into place and snap it into the latch on the back of the assembly. Push the electrical connection onto the bulb terminals, being careful not to bend the terminals.
Snap the bulb cover into place on the back of the headlight assembly and test the headlights by turning on the switch to verify the headlight is working. Turn off the lights and close the bonnet.