How Long Do Ignition Coils For Cars Last? - It Still Runs

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How Long Do Ignition Coils for Cars Last? by David Dunning

The ignition coil is the heart of an automotive spark ignition system, but is essentially just an electrical transformer. It consists of a primary coil made up of 100 to 150 turns of heavy copper wire and a secondary coil made up of 15,000 to 30,000 turns of fine copper wire.

Function

The primary coil creates, or induces, an extremely high voltage in the secondary coil. This causes a spark in the spark plug, which ignites the mixture of fuel and air in the engine.

Life Span

Federal law in the United States dictates that the ignition coil and ignition module on new vehicles are warranted for at least two years or 24,000 miles, whichever occurs first. The insulation in the ignition coil will degrade over time, but many coils are designed to last 100,000 miles or more.

Testing

You can test the resistance of the primary and secondary coil windings with an ohmmeter, with the battery lead to the ignition coil disconnected. You need to refer to the manufacturer's specification for your specific ignition coil, but typically primary coils have a resistance between 8,000 ohms and 20,000 ohms and secondary coils between 0.5 ohms and 2 ohms.

References

Family Car Parts: A Short Course on Ignition Systems
"Automotive Technology"; Jack Erjavec; 2005
Dodge: Warranties

Writer Bio

A full-time writer since 2006, David Dunning is a professional freelancer specializing in creative non-fiction. His work has appeared in "Golf Monthly," "Celtic Heritage," "Best of British" and numerous other magazines, as well as in the book "Defining Moments in History." Dunning has a Master of Science in computer science from the University of Kent.