DIY

How to Replace an Ignition Coil

Reading Time: 4 minutes

Are you a newbie looking for an easy repair project that you can do yourself? Many late-model cars have individual coil-on-plug (COP) ignition coils that are easy to replace⁠—with the COP design, each cylinder has an individual ignition coil sitting on top of the spark plug.

Typically, to remove this type of coil, all you need to do is disconnect its electrical connector, and remove its retaining fastener. Then, you can remove the coil from the vehicle.

Easy peasy, right?

Of course, there are some vehicles that have the coils buried under a bunch of other stuff. So, it’s a good idea to make sure yours are easy to access before digging in.

replacement-ignition-coil
Ignition coils fire the spark plugs by converting the low-voltage from the battery into the necessary high-voltage.

How to Change an Ignition Coil (COP design)

Ignition coils convert the low-voltage from the battery into the high-voltage needed to fire the spark plugs. Obviously, such a demanding role may cause the coils to wear out over time.

They can also fail due to external factors. Examples include high resistance in the secondary ignition circuit and contamination from engine oil.

Regardless of the cause of failure, a faulty ignition coil should be replaced right away. A bad coil can cause an engine misfire that eventually damages other parts of the vehicle (e.g., the catalytic converter).

With that in mind, are you ready to replace one of your COP ignition coils? Good, then let’s get started!

Tools Needed to Replace a COP Ignition Coil:

The tools needed to replace a COP ignition coil will vary, depending on what type of car you have.

In general, however, you’ll need:

COP Ignition Coil Replacement Instructions:

Before we begin, keep in mind: all vehicles are different. The information below is generic and for entertainment and educational purposes only. Be sure to follow the repair information for your specific application.

Repair manuals, such as those from Chilton, are useful, but a subscription to a repair database is even better. ALLDATA and Mitchell 1 both have single-vehicle subscriptions for DIYers that provide detailed factory repair information.

You can learn more about accessing quality repair information in this article.

ignition coils location
The ignition coils on a 2007 Honda Civic.

Ignition Coil Removal

  1. Put on your safety glasses.
  2. Make sure the engine and ignition are both off. The engine should also be cool.
  3. Clean the area around the ignition coil to remove any loose dirt or debris.
  4. Remove the ignition coil electrical connector. Usually, this involves pushing down on the connector’s tab while pulling the connector away from the coil.
  5. Use a ratchet and socket to remove the ignition coil retaining fastener(s).
  6. Pull the ignition coil up and away from the engine to remove it from the spark plug.
removing electrical connector
Remove the electrical connector from the coil.
removing the ignition coil fasteners
Use a ratchet and socket to remove the ignition coil fastener(s).

Ignition Coil Installation

  1. Compare the new ignition coil to the old ignition coil to ensure that both are the same design.
  2. Position the coil over the spark plug.
  3. Make sure the coil’s mounting hole lines up with the stud or hole on the engine.
  4. Press down on the coil gently.
  5. Reinstall the coil retaining fastener(s), then use a ratchet and socket to tighten it until it’s snug. If you’re unsure of how tight the fastener(s) should be, use a torque wrench to tighten it to the manufacturer’s specification. This information can be found in a repair manual or repair database.
  6. Reinstall the coil electrical connector. You’ll hear it click once it’s securely in place.
  7. Start the engine to check your work.
removing ignition coil from the spark plug
Pull the ignition coil up and away from the engine to remove it from the spark plug.
ignition coil mounting hole
Make sure the coil’s mounting hole lines up with the stud or hole on the engine.
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Author

Mia Bevacqua

Chief Mechanic at CarParts.com

Mia Bevacqua is an automotive expert with over 15 years of industry experience. She holds ASE Master, L1, L2, and L3 Advanced Level Specialist certification, as well as a bachelor's degree in Advanced Automotive Systems.

Throughout her career, Mia has applied her skills toward automotive failure analysis inspections, consulting, diagnostic software development, and of course, freelance writing. Today, she writes for companies around the world, with many well-known clients showcasing her work.

Mia has a passion for math, science, and technology that motivates her to stay on top of the latest industry trends, such as electric vehicles and autonomous systems. At the same time, she has a weakness for fixer-upper oddballs, such as her 1987 Chevy Cavalier Z-24 and 1998 Chevy Astro Van AWD.

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