How to use a spark plug tester?

How to use a spark plug tester?

Table of Contents



A spark plug tester is a valuable tool for diagnosing issues with the ignition system of an internal combustion engine. By using a spark plug tester, you can determine if the spark plugs are functioning properly and identify any potential problems. In this article, we will explore how to use a spark plug tester effectively.

Materials Needed

Before we delve into the steps of using a spark plug tester, let’s first gather the necessary materials:

1. Spark plug tester: You will need a spark plug tester, which is a device designed to simulate the spark plug firing process.

2. Safety equipment: It is always important to prioritize safety. Make sure you have safety glasses and gloves to protect yourself while working with the ignition system.

Step-by-Step Guide

Now that we have the required materials, let’s proceed with the step-by-step guide on how to use a spark plug tester:

Step 1: Safety first
Ensure the engine is turned off and the key is removed from the ignition. This will prevent any accidental starts while working on the ignition system.

Step 2: Locate the spark plugs
Identify the spark plugs in your engine. Depending on the engine type, they can be found on the top or side of the engine cylinder head. You may need to remove any engine covers or components obstructing access to the spark plugs.

Step 3: Remove the spark plug wires
Carefully remove the spark plug wires from the spark plugs. It is essential to remember the order in which the wires are connected to avoid mix-ups during reinstallation.

Step 4: Connect the spark plug tester
Attach the spark plug tester to the first spark plug wire. The tester usually has a connector that fits onto the spark plug terminal. Ensure a secure connection to obtain accurate results.

Step 5: Ground the spark plug tester
Ground the spark plug tester by attaching the tester’s grounding clip to a metal surface on the engine. This provides a path for the electrical current to flow during the testing process.

Step 6: Start the engine
With the spark plug tester connected and grounded, start the engine. Observe the spark plug tester for any signs of a spark. A healthy spark will be visible in the tester’s window or produce a consistent clicking sound.

Step 7: Repeat the process
Repeat steps 4 to 6 for each spark plug wire, testing them one by one. This will help identify any faulty spark plugs or ignition issues.


Using a spark plug tester is a straightforward process that can help diagnose ignition system problems. By following the step-by-step guide outlined in this article, you can effectively use a spark plug tester to determine if the spark plugs are functioning correctly. Remember to prioritize safety and consult a professional if you encounter any difficulties or need further assistance.