The ignition system provides the voltage needed to start your car. Ford uses a distributorless ignition system, sometimes called a direct ignition system, in the Ford Focus. This system depends on an ignition coil pack that usually contains three ignition coils.
Understand basic safety procedures. Any time you work on your Ford Focus, you should set the emergency brake and disconnect the negative, or ground, cable from the battery. Some mechanics recommend you isolate the cable to prevent accidental contact, which could spark a connection.
Release the spark plug wires from the Ford Focus ignition coil pack. You may need to pinch or press a release to unlock the wires.
Use a socket set or a small wrench to unbolt the ignition coil connectors. You also need to undo the capacitor electrical connectors. As you work, make note of which connectors go where--this pays off you when you reassemble the parts.
Locate the bracket that holds the ignition coil pack and the electrical capacitor in place. Undo the fasteners that secure them.
Separate the Ford Focus ignition coil pack from the mounting system. Replace the old Focus ignition coil pack with a new one. Verify the new ignition coil pack works with your engine, even if you use a universal ignition coil pack.
Reassemble the parts. If you have a Torque wrench, use it to tighten the ignition coil bolts with 7 inch pounds of torque (10 Nm).
For the 2005 Ford Focus ZX4 ST, you need to use a Focus ignition coil rather than an ignition coil pack. The replacement process may need slight variation.