How to Test an Ignition Coil

The ignition coil is an integral part of the vehicle’s ignition system, transforming the battery’s low voltage to the thousands of volts needed to spark the spark plugs and start the engine. This blog post aims to provide drivers with an understanding of ignition coils, including how to test them with a multimeter, their function, and lifespan.

How Long Does an Ignition Coil Last?

The lifespan of an ignition coil can vary widely depending on the vehicle and its usage. Generally, an ignition coil should last around 100,000 miles or more. However, this can be shorter or longer based on factors such as driving habits, environmental conditions, and the quality of the coil itself. Regular maintenance and checks can help ensure that your ignition coil remains in good condition for as long as possible.

Symptoms of a Failing Ignition Coil

Identifying a failing ignition coil early can save you from more significant engine problems down the line.

  • Engine misfires
  • Poor fuel economy
  • Reduced power
  • Difficulty starting the engine
  • Check Engine light turns on

If you notice any of these signs, the ignition coil likely needs to be replaced.

How to Test an Ignition Coil with a Multimeter

Testing an ignition coil with a multimeter is a straightforward process. Here’s how to do it:

  1. Locate the Ignition Coil

First, you need to locate the ignition coil in your vehicle. It’s usually found on or near the engine and fairly close to the distributor. Refer to your vehicle’s manual for the exact location. Wear protective gear such as safety glasses and gloves to protect yourself from potential sparks or electrical shocks.

  1. Prepare Your Multimeter

You’ll need a digital multimeter capable of measuring resistance. Set your multimeter to the 20k ohm setting. This setting is appropriate for testing the primary and secondary windings of your ignition coil.

  1. Disconnect the Ignition Coil

Before proceeding, make sure your vehicle is off and the key is removed from the ignition. Disconnect the ignition coil from the vehicle’s wiring harness.

  1. Test the Primary Windings

To test the primary windings, locate the positive (usually marked with a “+”) and negative (“-”) terminals on the coil. Place the multimeter’s red lead on the positive terminal and the black lead on the negative terminal. A normal reading for primary windings is between 0.4 and 2 ohms. If your reading is outside this range, the coil may be faulty.

  1. Test the Secondary Windings

Next, test the secondary windings. Place the multimeter’s red lead on the coil’s output terminal (where the spark plug connects) and the black lead on the negative terminal. A normal reading for secondary windings should be between 6,000 and 15,000 ohms. Again, readings outside this range suggest a problem.

What to Do If Your Ignition Coil Fails the Test

If your ignition coil fails the multimeter test, it’s likely defective and needs replacing. Driving with a faulty ignition coil can lead to engine damage, reduced performance, and increased emissions. Therefore, it’s advisable to replace a faulty coil as soon as possible.

If the car battery is low or dead and you’re looking to jump-start the car, we have a helpful guide here that can help.

If you’re not confident doing this test on your own, seek professional advice. We recommend getting it checked and replaced if needed as soon as possible to prevent further damage to the vehicle. If you need the ignition coils repaired or replaced, ClickMechanic can help. Get an instant price here.

Marketing at ClickMechanic

Louanne is a marketing and communications professional in the automotive tech industry currently at ClickMechanic, boasting over 5 years of experience.

Louanne’s work at ClickMechanic might revolve around branding and customer engagement, but her passions extend far beyond the marketing sphere. A true foodie at heart, she loves exploring diverse cuisines and talking about her culinary adventures across the world. Her writing prowess shines through in her car-related blog content, where she offers invaluable driving tips and practical car repair advice.

In her Suzuki Jimny 4-wheel drive, Louanne combines her sense of adventure with her automotive know-how, transforming every drive into a lesson and a pleasure.