How to Change Spark Plugs on Your Car In 8 Steps

For many, the modern vehicles they drive seem like a very complicated mish-mash of machinery. Though advancement in vehicle technology has come a long way and made that statement true for more and more people, there are some areas that are still easily serviceable no matter how high-tech they are. One of those serviceable areas is your spark plugs. Really all you need when asking how to change spark plugs are a few basic tools and the ability to follow some simple steps.

This article will give you a step-by-step guide to help you learn how to change spark plugs.

Things You Will Need

  • Ratchet- 3/8 inch is usually standard;
  • Spark plug socket (Also called a gear wrench);
  • Swivel socket adapter;
  • Ratchet extension (also 3/8”);
  • Gap gauge;
  • Degreaser spray;
  • Shop towels for clean up.

How to Change Spark Plugs Step-by-Step

Step 1 – Preparation

Gather all of the tools you need for this process to make things go quickly and smoothly as you learn how to change spark plugs. Be sure to consult your owner’s manual to ensure you purchase the correct type and size spark plug for your specific vehicle. You do not have to change your spark plug wires every time you do your plugs, but if you need to, now is a good time to do so. You may also want an old towel or blanket so that you can drape it over your fenders to help protect your paint. Finally, disconnect the positive terminal on your car battery since you will be working on an electrical component.

Step 2 – A Bit of Tidying Up

Be sure your engine has had plenty of time to cool. This will keep any fire risk down and will also ensure the new spark plugs tighten correctly since heat will expand the threads on your engine. Clean the area around each plug thoroughly with your degreaser spray and shop towels. Doing this step will keep any dirt, gunk, or debris from falling into the open holes that lead directly into your engine once the plugs are removed. Be sure to use protective glasses when using the spray.

Step 3 – Beginning the Process

As you remove the plugs, you will want to keep them in order ensuring each plug socket and wire matchup. This will make it easier when you place them back into position and will keep you from accidentally reconnecting the wrong plug to the wrong wire.
Remove the first wire and plug.

Step 4 – Set up Your Tools

Once the first wire and plug set is removed, fit the required combination of extensions and swivels to the spark plug socket so that it properly fits the plug.
Using the tool, turn it counter-clockwise to loosen the plug from the wire. Though you have taken the time to clean ahead of time, you still have the risk of accidentally dropping dirt or debris into the engine. If you find it hard to get the plug loose, do not force it or you may break it off in the plug and make the process much more difficult. Use an anti-seize lubricant and allow it to soak to try and help loosen it.

Step 5 – Check the Gap

The next step of how to change spark plugs is to use your gap gauge to check there is proper gapping on your new plugs. To do so measure the gap between the two electrodes (the hook-shaped one and the center pin) and compare it to the proper gap setting specified by your manual.

Most plugs come pre-gapped from the factory but shipping or rough handling may compromise the gap. An improper gap results in an improper spark so it is always a good idea to take the time to double check. Adjust the gap if you need to.

Step 6 – Replacing

Once you have made sure the gap is correct, carefully place the plug into the open hole. You can treat the plug with anti-seize to help it from locking up. Using a clockwise motion, gently screw the plug back in by hand ensuring the threads are mated properly. Finish tightening it in using your socket tools.

Do not overtighten the plug. You only need it to be tightened enough that the washer of the plug comes in contact with and is slightly compressed to the shoulder of the hole.

Step 7 – Wire Replacement

Now that the plug is properly in place, reattach the wire by applying a little force while pushing and twisting the boot back onto the exposed plug tip until you feel it click back in place. That click lets you know it is seated correctly.

Step 8 – Repeat

Use the previous steps to replace each of the plugs. Doing one at a time saves you from getting wires confused and possibly ending up with an engine misfire. If you need to replace your wires as well, go back around and do them one at a time too. You will notice the wires are not all the same length since they have proper installation positions. Thus, you will want to match each new wire to the old one to be sure you get them in the correct position.

Do not forget to mark down your mileage so that you have a reminder as to when you will need to replace your spark plugs again.


Your vehicle does not have to be a mystery. Certain aspects can be taken care of and maintained by even the greenest DIYer. Your spark plugs are one thing you can easily learn to do yourself. With a few tools and some simple steps, you too can learn how to change spark plugs.

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