What is an Ignition Coil?

Welcome to Mercie J Auto Care, Where Compassion and Craftsmanship Come Together. I'm Rick Smith, ASE Certified Master Technician. Ignition coils typically fit in the palm of your hand. They are heavy because they have a lot of tiny wire inside. Most of our modern engines have a coil at each cylinder, so if you have a GMC truck like mine you will have 8 coils, but if you have a Honda Pilot like my wife you will have 6. Coils often last the life of the vehicle, but they are electronic devices so occasionally do fail. The job of the coil is to increase the voltage from about 13 volts to more than 10,000. The best way to protect the coil is to replace the spark plugs at the proper interval. Most manufacturers recommend about every 100,000 miles. Interestingly enough studies have shown that after about 60,000 miles it takes more energy to fire a spark plug and therefore puts stress on the coils, so doing the spark plugs a little early can be a wise investment.