How to Test an Ignition Coil with a Multimeter

How to Test an Ignition Coil with a Multimeter

How to Test an Ignition Coil with a Multimeter


The ignition coil is a vital component in a vehicle's ignition system. It plays a crucial role in generating the high-voltage spark that ignites the air-fuel mixture in the engine's combustion chamber. Over time, ignition coils can wear out or develop faults, leading to poor engine performance or even engine misfires. Fortunately, you can test an ignition coil's functionality using a simple tool called a multimeter. In this blog post, we will guide you through the step-by-step process of testing an ignition coil using a multimeter.

Step 1: Gather the Necessary Tools

Before you begin testing the ignition coil, make sure you have the following tools ready:

  • Multimeter:Choose a digital multimeter with settings for resistance (ohms) and voltage (volts).
  • Safety Equipment:Wear safety goggles and gloves to protect yourself from any potential electrical hazards.


Step 2: Prepare the Multimeter

Set your multimeter to the resistance (ohms) setting. Typically, this setting is represented by the Greek letter "Ω" on the multimeter's dial.


Step 3: Disconnect the Ignition Coil

Locate the ignition coil in your vehicle's engine bay. It is usually a cylindrical component with several wires connected to it. Start by disconnecting the electrical connectors and spark plug wires from the ignition coil. Refer to your vehicle's manual if necessary.


Step 4: Measure Primary Coil Resistance

Identify the terminals on the ignition coil. It should have two primary terminals labeled "B+" or "15" (power supply) and "C" or "1" (negative or ground). Place the multimeter probes on these terminals, ensuring a good connection.Observe the multimeter reading. The primary coil resistance typically ranges from 0.2 to 3 ohms, depending on the vehicle's make and model. Refer to the manufacturer's specifications for the acceptable range.


Step 5: Measure Secondary Coil Resistance

Locate the secondary terminal on the ignition coil, often labeled "HT" or "Spark Plug." With the multimeter still set to resistance mode, connect one probe to the secondary terminal and the other probe to the ignition coil's negative terminal (C or 1). The secondary coil resistance should typically be in the range of 6,000 to 30,000 ohms, depending on the coil's design. Again, consult your vehicle's manual for the specific range.


Step 6: Test for Voltage Output

Reconnect the electrical connectors and spark plug wires to the ignition coil. Start the engine and let it idle. Carefully insert the multimeter probes into the spark plug wire boots, ensuring they make good contact with the metal terminals. Observe the multimeter reading, which should show a voltage ranging from 20,000 to 50,000 volts, depending on the coil and the vehicle's specifications.


Step 7: Compare Readings and Consult Professional Help

Compare the readings obtained during the resistance and voltage tests with the manufacturer's specifications. If the readings are outside the acceptable ranges, it indicates a faulty ignition coil.  In such cases, it is advisable to seek professional assistance or replace the ignition coil yourself if you have the necessary knowledge and experience.



Testing an ignition coil with a multimeter is a straightforward process that can help diagnose potential issues and ensure your vehicle's optimal performance. By following the steps outlined in this blog post, you can determine whether your ignition coil is functioning properly or if it requires further inspection or replacement. Remember to prioritize safety and consult your vehicle's manual for specific instructions related to your make and model.


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