What Is an Ignition Coil?
An ignition coil is a step-up transformer that converts the vehicle's 12V battery voltage to the 20,000-40,000V needed to generate a spark across the spark plug gap. Modern engines use coil-on-plug (COP) systems with one coil per cylinder, replacing the older distributor and ignition wire systems.
Types
Coil-on-plug (COP): Mounts directly on the spark plug. Coil pack: Multiple coils in one unit for waste-spark systems. Canister coil: Traditional single coil with distributor. See our Ignition System Blog for diagnostics.
Frequently Asked Questions
How do I know if an ignition coil is failing?
Symptoms include engine misfire (rough idle, hesitation), check engine light with misfire codes (P0300-P0304), reduced fuel economy, difficulty starting, and sometimes a visible spark at the coil boot. A failing coil can also damage the catalytic converter due to unburned fuel.