How does a spark plug tester work?

Written by steve smith
  • Share
  • Tweet
  • Share
  • Email

A spark plug tester tests to see if a spark plug is accepting current from the spark plug wire. When a charge is sent through the spark plug wire to the plug, it will create a spark. The spark plug won't work if there is no charge going through it. The tester is used to see not only if the spark plug is firing but if the wire is conducting electricity. It will help you see whether or not the sparks are firing during combustion.

Other People Are Reading

How it Works

Disconnect the spark plug wires from the plug you want to test. Hook the spark plug wire to the tester end. Then clamp the spark plug tester up to the engine block. This will ground the unit and allow the charge to pass through it. Now, fire up the engine and watch the end of the spark plug tester for sparks. If you see sparks then the wire is good and the plug is bad and should be replaced. It's a simple process of elimination, finding which piece of equipment is not working, by finding the ones that are.

What is a Spark Plug Tester

A spark plug tester is basically a spark plug with a grounding mechanism. It looks something like a spark plug with a white body, metal end and tubular shape. The metal grounding clip looks like a simple clip you'd find on an ID badge. This is what separates a spark plug tester from an actual spark plug. It's main role is to allow you to test spark plugs without removing them, saving time and money.

Don't Miss


  • All types
  • Articles
  • Slideshows
  • Videos
  • Most relevant
  • Most popular
  • Most recent

No articles available

No slideshows available

No videos available

By using the site, you consent to the use of cookies. For more information, please see our Cookie policy.