Leading Causes Of Ignition Coil Failures

Leading Causes Of Ignition Coil Failures

It may be surprising to learn that the leading causes of ignition coil failures have nothing to do with the coils themselves. Ignition coil damage is often caused by underlying issues never addressed in engine misfire repairs. Issues like spark plug gapping, leaking valve covers or moisture intrusion.

Sponsored by NGK Spark Plugs


It may be surprising to learn that the leading causes of ignition coil failures have nothing to do with the coils themselves. Ignition coil damage is often caused by underlying issues never addressed in engine misfire repairs. Issues like spark plug gapping, leaking valve covers or moisture intrusion.

A proper spark plug gap is crucial to an ignition system and the health of an ignition coil. A worn or excessive gap will cause an ignition coil to work overtime, using more voltage to bridge the gap and create spark inside of the cylinder. This increase in voltage stresses the internals of not only the ignition coil but, in certain circumstances, the driver of the ECU. When the driver in the ECU fails the coil will no longer create spark, leaving a dead cylinder.

To ensure proper spark combustion and to prevent coil damage, refer to the spark plug manufacturer’s gap specifications. It is important to remember that many spark plugs come pre-gapped according to the applications that correspond to each spark plug part number. In the event that there is a coil failure due to an excessive gap, the spark plug and ignition coil should be replaced. It is also recommended that the ECU driver is verified for proper operation.

Oil Valve Leakage into Spark Plug Tubes

Moisture is another cause of ignition coil damage, coming from the most likely and unlikely of places. The most likely being an oil leak from the valve cover gasket. On many COP-style engines the spark plug and ignition coil are mounted into a tube that is a part of the valve cover. Overtime the seal between the valve cover and that spark plug tube can fail, causing oil to leak in and fill up around the spark plug and ignition coil. This in turn can lead to spark plug and ignition coil failure. Be sure to fix the root cause of the oil leak, so this problem does not reoccur with the new ignition parts installed.

Water intrusion is an unlikely, and therefore, overlooked cause of ignition coil damage. In some vehicles, A/C condensation can build up and drip directly onto ignition coils, filling up spark plug holes with water. To solve this problem, some ignition coil manufacturers pre-apply or include a marine-grade di-electric grease with their product. This gives a better seal between the coil-on-plug boot and the spark plug terminal nut, preventing moisture from interfering with voltage transfer and spark generation.

Taking steps to check for oil leaks, moisture, and spark plug issues will prevent serious engine damage and other ignition-related headaches. There are thousands of reasons for misfire codes. Don’t stop at ignition coils when diagnosing them.

For more information or questions about ignition coils, you can reach out to the NGK Technical Support line by calling 877-473-6767 or visit them on the web at www.ngksparkplugs.com/ignitioncoils.

You May Also Like

A Closer Look: Gasoline Direct Injection (GDI)

Gasoline direct injection (GDI) is used on most new vehicles and requires a different approach to diagnosis and service. GDI technology has been an integral part of helping to improve fuel economy while reducing emissions, and can be found on more than half of the U.S. fleet. In fact, the use of GDI engines has

Gasoline direct injection (GDI) is used on most new vehicles and requires a different approach to diagnosis and service. GDI technology has been an integral part of helping to improve fuel economy while reducing emissions, and can be found on more than half of the U.S. fleet. In fact, the use of GDI engines has grown by over 600% since 2010. This means that in the next five years, 42 million more vehicles with GDI will enter the Aftermarket “Sweet Spot” of 6-12 years old, during which their injectors and related parts may need to be serviced or replaced. While GDI systems have proved effective, these systems encounter specific failures and require an understanding of how they work and how to test them when they set a code.

A Closer Look: Electronic Throttle Bodies

A shop’s reputation is affected by things like accuracy of diagnosis, quality of the repair, and friendly service. Equally as important is the quality of the parts installed. If the shop does everything right, and the part fails, the customer will ultimately be upset with the shop. When a new part fails, the customer is

Enhancing Efficiency and Streamlining Operations: The Benefits of Utilizing Nexpart Multi-Seller for Repair Centers

In today’s fast-paced automotive repair industry, staying ahead of the competition is crucial for repair centers to thrive. One key aspect that can significantly impact operational efficiency and customer satisfaction is the availability of OE, Aftermarket, Heavy Duty & Salvage parts. Here are just a few advantages of incorporating Nexpart Multi-Seller, a cutting-edge parts ecommerce

Get your vehicle road trip ready with these summer tips 

Summertime is a great time to take your car out on the open road, but it’s also important to ensure that your vehicle is in tip-top shape. Regular preventative maintenance can help you avoid costly repairs and keep your car running smoothly. Make sure you’re ready with these helpful tips from Delphi Technologies. Chassis The

A Closer Look: Ignition Coils

OE coils are known for their high failure rates. Engine misfires, rough idle, a decrease in power under acceleration, poor fuel economy, and a check engine light are all signs of an ignition coil that has failed. Read along for more technical information on how to diagnose a failed coil, and why the original equipment

Other Posts

Mayhew Tools Introduces Spark Plug Thread Chaser

This tool is made in USA and is backed by a lifetime warranty.

Ignition Systems

The ignition coil is a very simple and robust circuit.

Do You Know The Cause Of A No-Spark Condition?

A no-spark condition could be the result of communication errors or missing data from a dead module.

NGK Spark Plugs Expands Spark Plug, Ignition Coil Coverage

Expansion includes 15 new spark plug part numbers, many with high ignitability designs.