An ignition coil is a high voltage transformer in your ignition system, which transforms the battery's low voltage, to the thousands of volts needed by the spark plugs to start your engine and keep it running smoothly. We recommend getting your ignition coils checked during your recommended service intervals. However, if your car won’t start, or the engine misfires, chances are your ignition coil is malfunctioning. If your ignition coil is not working properly, it will not be able to create the spark to ignite the air & fuel mixture, causing 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. And without a spark, your car won’t start, might stall, and might leave you stranded. From an environmental point of view, there is no impact from ignition coil replacement.