How To Test an Ignition Coil

Updated: Jan. 31, 2024

Test the ignition coil quickly and easily with a simple ignition system tester

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Learn how testing the ignition coil can be quick and easy using a special ignition system tester. It's inexpensive and works for any small engine.

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Step 1

Testing the Ignition Coil and Spark Plug

Most people think you can check a small engine’s ignition system by removing the spark plug and grounding it while cranking the engine and watching for a spark. Nope. That just confirms that the spark plug fires in open air. It doesn’t mean the ignition coil is strong enough to fire the plug when under full compression.

Here’s a better ignition coil test.

Buy an inexpensive ignition system tester then connect the tester between the spark plug boot and the engine. Watch for a spark in the tester window as you pull the starter cord. To test the operation of both the ignition coil and the spark plug, connect the tester between the spark plug boot and the spark plug. Then start the engine and watch the tester window. A spark plug misfire will immediately be evident in the tester window.

You can use the tester on any small engine (mower, snow blower, chain saw, string trimmer, etc.).

How To Test An Ignition Coil Testing the Ignition Coil and Spark PlugTMB Studio