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What Problems Can a Bad Ignition Coil Cause?

What Problems Can a Bad Ignition Coil Cause

Ignition coil is one of the most important parts of the ignition system. It transforms low voltage into thousands of volts to create sparks in the ignition plugs.

Bad ignition coils can cause a variety of difficulties in the ignition system. So you have to check and find out the faulty ones and replace them at your earliest convenience.

In this article, I’ll discuss the problems a bad ignition coil can cause, and the process of diagnosing this essential component.

5 Problems That A Bad Ignition Coil Can Cause

With bad ignition coils, the engine will face the following problems.

Difficulty in Starting the Engine

A bad ignition coil may cause difficulty while starting the engine. If you start your car with one faulty coil, then it will create less hassle. But if your engine has a couple of faulty coils, it will cause a serious problem. Faulty ones even can cause your car not to start.

Engine Misfiring or Stalling

This one is another common problem that can be caused due to bad ignition coils. Faulty ignition coils may stop your car suddenly.

Poor mileage

Among many other problems, poor fuel economy is a serious one. Faulty ignition coils decrease the mileage of your engine. It even can reduce the overall performance of the engine.


Bad ignition coils can cause vibrations in your vehicle. This problem may occur for several reasons. But having faulty spark coils is one of the main reasons for vibrating your vehicle.


If the ignition coil consists of faulty coils, backfiring may occur. That means you will see emissions through the exhaust pipe of your vehicle.

Alright, I’ve discussed the problems of having bad spark coils. However, the only solution is that you need to change the bad coils with new ones. And it is the most effective way of getting a smoother riding experience.

What Are The Types of Ignition Coils?

You must know the types of ignition coils in order to fix the problems of ignition coils. It is even a must-know thing if you want to change the coils. Alright, here are the 3 different types of ignition coils below:

  1. Coil-On-Plug (COP)
  2. Coil-Near-Plug (CNP)
  3. Coil-Per-Cylinder (CPC)

Coil-On-Plug (COP) is the most common type among the three options.

How to Test the Ignition Coil?

Checking an ignition coil can be dangerous if you can’t do it properly. This guide will just help you to apply your expertise. If you are completely a novice, then you should consult with an expert. However, if you love to DIY, then carefully follow the step-by-step guide below.

You need the following tools to perform this action.

  • OBD II scanner
  • Multimeter
  • Spark tester
  • Socket set
  • Ignition coil puller

Step-1: Removing your ignition coils

  • Park your car on your yard or any other even surface.
  • Turn the engine of your car off, and wait until it’s cool enough.
  • Remove the ignition coil using the ignition coil puller. You can also use the socket set to perform this task.
  • You have to use an OBD-II scanner to check OBD-II. If you find codes from P0300 to P0312, then the engine is facing a misfires problem. And the codes from P0350 to P0362 indicate that the ignition coils have some issues.
  • It’s better to inspect the sparking plugs during that time. If you find any fault, replace that immediately.
  • Again, concentrate on your ignition coils, and inspect the housing for holes, cracks, or any other damage.

Step-2: Checking your ignition coils by using a spark tester

  • First, plug the spark tester into the coil.
  • Then connect the ground wire.
  • After that, plug into the coil connector.
  • Fix the spark gap correctly if it is not appropriate at all.
  • Then start the engine to test the coils. If the spark is created properly, then the coil is okay at all. Or else, the coil is faulty.

Expert’s tips: “By using a multimeter, you can easily test the ignition coils by checking the resistance on both the primary and secondary circuits.

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