An ignition coil is a high-voltage transformer in your ignition system. It transforms the battery's low voltage to the thousands of volts the spark plugs need to start your engine and keep it running smoothly. We recommend getting the ignition coils checked during your recommended service intervals. If your car won’t start, or if the engine misfires, chances are your ignition coil is malfunctioning. If it’s not working properly, it won’t be able to create the spark to ignite the air and fuel mixture. This will cause a backfire or misfire. Replacing the ignition coil is an inexpensive repair compared to the damage that can be done. A bad ignition coil can severely damage the catalytic converter or even your entire engine. Without a spark, your car won’t start or might stall, leaving you stranded. From an environmental point of view, there is no impact from ignition coil replacement.