What is the Auto Ignition Coil?

The auto ignition coil is one of the essential parts in a vehicle's spark plug-based system. It transforms battery voltage into the higher voltage required to jump the spark plug gap, ignite the air-fuel mixture and set your car's pistons into motion. It's a complex electrical component with two separate coils of wire wrapped around an iron core. The primary coil, which receives the battery's 12 volts, acts as an electromagnet that creates and then collapses a magnetic field to induce current in the secondary coil. This current is transformed into 15,000 to 25,000 volts by the secondary coil and passed on to the spark plug.

In some older vehicles, the ignition coil may look like a small metal cylinder (sometimes referred to as a "canister-type" coil) with wires sprouting out of it. These wires connect it to the battery and then to the contact points in a distributor that is part of a traditional spark plug-based ignition system. The opening and closing of the circuit in the distributor is coordinated with the rotation of the engine, so that a burst of high-voltage electricity reaches the spark plug at just the right time to fire it.

Most modern car engines, however, do not use a distributor and instead run the ignition coil directly to each spark plug. The modern version of the ignition coil looks very similar to a rubber boot that slips over the spark plug and it can be disassembled to reveal several meters of tightly-wound copper wiring inside. The coil pack is made up of two insulated coils, with the secondary coil having thousands more windings than the primary. It uses the'step-up transformer' principle to step up the on-board 12 volts available in the battery to the required ignition voltage and then passes that on to the spark plug.

When an ignition coil starts to fail, it can cause your vehicle's spark plugs to fail to perform their job of firing the air-fuel mixture and setting the pistons into motion. It can also affect the efficiency of your catalytic converter, which is designed to absorb some of the unburnt fuel that would otherwise be doused into the environment. In extreme cases, prolonged operation of a defective ignition coil can actually irreversibly damage the catalyst internal media.

The simplest way to diagnose an ignition coil problem is to isolate the faulty coil and replace it with a good replacement. However, if the trouble is widespread, replacing all of the coils in the ignition system will likely be a more cost-effective solution.