How To Replace An Ignition Coil

　　What is an ignition coil?

　　A car ignition coil is a transformer that receives the low voltage of the battery and produces thousands of volts. This very high voltage is necessary to jump the gap on the spark plug to create the spark needed for combustion. On older engines, ignition coils or built-in distributor ignition coils, or fix it nearby and supply the spark to the distributor. In modern engines, a computer (module) has replaced the distributor and commanded the ignition coil to fire. Computer control of spark timing allows for very precise spark plug ignition about piston and valve movement - improving fuel economy, emissions, and power. The coil can be mounted on each spark plug or in a package with each spark plug's cable.

　　What are the symptoms of a worn or malfunctioning ignition coil?

　　No spark means the engine has failed to fire, or in the case of a large coil, one is not running. Ignition coils often fail due to aging. The plastic casing becomes brittle when heated, and the metal core fatigues from the high pressure. Sparks will leak through the housing or fail to reach the spark plugs. Either way, the coil needs to be replaced. Although coils may be considered "commissioning" parts, most manufacturers do not publish coil service sheets.

　　How often should I replace a faulty ignition coil?

　　as soon as possible. A breakdown of this type is likely to leave you stranded on the side of the road. Even when the car is still moving, a misfire can damage other parts of the engine, especially the catalytic converter. Your best bet is to find a reputable mechanic as soon as possible and make an appointment. Most coil changes can be done the same day, but times do vary by make and model, so plan to drop off. Think of the last spark plug replacement or "tune" you made to your car. Replacing the plug at the same time as the coil can save you some time and money.