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To DIY or Not to DIY:
Spark Plugs

January 29, 2020

Although spark plugs are small, they can make a huge difference in how your engine runs. On some cars, spark plugs are relatively easy to replace. On others, they can be much harder to get to. In this latest DIY article, we’ll examine the benefits and drawbacks of doing the job yourself.

Don’t DIY – You May Install the Wrong Plugs (or Get Bad Advice)

There are many different brands of spark plugs. It can be difficult to know which ones are correct for your engine. There are four primary types of spark plugs.

They are:


It might be tempting to install the cheapest option, but if you use the incorrect spark plug, your car may experience engine performance problems – and even severe engine damage. The easiest way to find out which spark plugs are right for your vehicle is to look in your owner’s manual.

DIY – You’ll Help Keep Your Engine Running Well

Your spark plugs’ job is to create a small spark that ignites the air/fuel mixture inside the engine. Spark plugs that are severely worn can cause your engine to misfire – and that can eventually damage the catalytic converter. Also, in some extreme cases, a worn-out plug’s electrode may break off inside the engine, causing extensive damage.

Signs that your spark plugs may be worn out include:

In many cases, however, you won’t be able to tell when it’s time to swap out your spark plugs. So, the best way to tell when it’s time for replacement is to follow the manufacturer suggested maintenance interval, outlined in your owner’s manual.

Don’t DIY – You’ll Need Some Specialized Tools and Products

Anyone who has an interest in wrenching will likely have most of the required tools to change a set of spark plugs. However, there are a couple of specialized tools and products you’ll need before you start.

Here’s our list of recommended tools:


You may not need all of these tools, but as a general rule, you’ll want to keep them on hand. Additional tools may be required depending on how easy (or how difficult) it is to get to your spark plugs.

DIY – You’ll Save Money on Installation

Changing a set of spark plugs is a relatively straightforward task on some cars. In other instances, the job can be a nightmare. Some plugs are hard to get to or may have engine components that need to be moved out of the way first. But hey, look at it this way: By doing the job yourself, you will save money on labor costs.

Don’t DIY – You Could Risk Damaging Your Engine

As with anything you do in life, it’s worth knowing the risks before you get started. Incorrectly removing or installing spark plugs can cause damage to your engine. Also, care needs to be taken when removing spark plug wires, especially if you plan to reuse them.

It’s possible to damage the threads inside the engine when installing the spark plug. And that can be a costly mistake. Also, the engine must be cool before removing the spark plugs or thread damage may result. , if dirt or debris gets into the spark plug well, it can get into the engine, causing damage, as well.

Finally, if you install the wrong sized spark plugs, the tips can make contact with the pistons inside the engine, leading to extensive damage.

DIY – You’ll Learn a New Skill

While the level of difficulty varies from car to car, if you do decide to DIY, you’ll end up learning a useful new skill. Replacing your spark plugs by yourself is a great way to learn more about your car and build confidence in your car maintenance abilities. While you’re under the hood, you can take a look at other components of the engine. Take this time to inspect items like the air filter and fluids like the engine oil, coolant, and brake fluid.

Don’t DIY – You’ll Need to Properly Check the Spark Plug Gap

Some spark plugs come pre-gapped, while others require you set the gap yourself. Even on plugs that come gapped, it’s a good idea to double-check the gap before installing the plugs. A smaller than normal gap will cause a weak spark and poor ignition of the air/fuel mixture. If the gap is too wide, the spark plug will not spark properly. The recommended gap is usually printed in your owner’s manual. To check and/or adjust the gap, you’ll need a gapping tool or feeler gauge.