Changing your spark plugs is an essential part of vehicle maintenance. With the right tools, you can do it yourself and save money compared to taking your car to a shop. In this guide, we’ll walk you through the process of changing spark plugs on a 2003 Toyota Corolla using a Performance Tool spark plug change kit.

Why Change Your Spark Plugs?

Over time, old spark plugs can affect your car's performance. New spark plugs ensure clean combustion, improve fuel efficiency, and help your engine run smoothly. Ignoring worn-out spark plugs can lead to poor engine performance and even engine damage. Spark plugs can become contaminated with oil, collect carbon buildup, the electrodes can become corroded due to overheating, or they can just lose efficiency through regular wear and tear. It's easy to make the change, and well worth it.

Overview

Here are the key steps in changing spark plugs that we will be performing:

• Getting under the hood, and accessing the coils or spark plug wires
• Removing the electrical connectors CAREFULLY to avoid damage
• >Removing coils or spark plug wires and removing the old plugs
• Ensuring our new spark plugs are the correct size and gapped correctly
• Installing the new spark plugs and making sure they're torqued to spec inside the engine
• Reinstalling all components and checking our work

This process can take around an hour in a simple vehicle, but can be more complex/time consuming in larger or more advanced engines or where the spark plugs are difficult to access (consult your owner's manual).

Before You Begin: Gather Your Tools

Start with all the necessary tools for the job. Here’s what you’ll need:

• W38905 Mechanic's Socket Set - this tool kit has a range of socket sizes for all kinds of jobs under the hood. It also includes some common spark plug socket sizes.
• W1264 Magnetic Parts Tray - this parts tray prevents lost tools and parts under the hood. It keeps all your metal parts in one easily accessible place.
• W80535 Spark Plug Gap Tool - sometimes spark plugs arrive from the factory with an improperly set gap. This gap tool can measure and adjust the gap for perfect combustion.
• W80534 Spark Plug Removal Tool - long and flexible tool to safely position and thread spark plugs in hard-to-reach locations.
• M200DB Torque Wrench - this torque wrench helps you achieve the perfect torque on things like lug nuts, bell housing bolts, and even spark plugs!
• W89011 Nitrile Gloves - your engine can be greasy, oily, dusty and nasty. Keep your hands clean but maintain dexterity with these nitrile gloves.

Having the right tools at your disposal will make the job quick and painless.

Step 1: Disconnect the Battery

Always begin by disconnecting the battery to prevent any shocks or shorts while you work on electrical components under the hood. This is a good practice anytime you're working on a car.

Step 2: Disconnecting the Coils

In this vehicle, the coils are secured to the valve cover with 10 mm bolts. We’re using our W38905 mechanic's socket set to remove them. If you’re working on a different vehicle, the coil mounting location may vary—some may be bolted directly to the engine or even the intake manifold instead of each cylinder.

Once you’ve removed the bolts, gently pry the electrical connector off the coil using your hands or a screwdriver. Be careful here to avoid breaking the electrical connectors or the plastic housing that surrounds them.

Step 3: Removing the Coils

At this point, you can take off the ignition coils. All vehicles are different, but they can usually be lifted out without the need for tools.

Step 4: Remove the Spark Plugs

Now it’s time to grab your spark plug socket. Our kit has a range of sizes to fit your spark plugs. Spark plug sockets have rubber inside that is gentle on the delicate ceramic spark plug body. In this case, we’re using the 5/8 in. socket.

Step 5: Check/Gap the New Spark Plugs

Before installing the new spark plugs, make sure they’re the correct size. They shouldn’t be longer or shorter than your current ones. It’s also important to check the gap of your new spark plugs. For the 2003 Toyota Corolla, the gap is 0.043 inches. You can use a spark plug gap tool to adjust the gap if necessary.

Step 6: Install the New Spark Plugs

Our spark plug installer is long and flexible, making it easy to gently insert the spark plug into the engine. This minimizes the risk of cross-threading or damaged threads inside the engine, which is the most important thing to avoid as you remove or install spark plugs. Once the spark plug is in place, install it until it’s snug using a ratchet like the one found in our W38905 socket set.

Step 7: Torque Spark Plugs to Spec

After that, use a torque wrench along with your spark plug socket to ensure that the spark plugs are torqued to the manufacturer’s specifications. For the Corolla, that’s 18 lb-ft. We're using our M200DB torque wrench to achieve the perfect torque.

Step 8: Reassembly

Now that the new spark plugs are installed, it’s time to reassemble everything under the hood. Use the same tools to plug the spark plug wires into the spark plugs, plug the electrical connectors back in to the coils, and double check that everything is plugged in correctly and fits snugly.

Step 9: Reconnect the Battery

Don’t forget to reconnect the battery! Make sure your hands and all tools are clear of all components that may spin or produce electricity once the battery is connected.

Start the Engine

Once everything is back in place, it’s time to start the vehicle. Make sure that there are no misfires and the car idles smoothly.

Check out the car phone!

You're Done!

Congratulations! You’ve just changed your spark plugs and saved potentially hundreds of dollars over taking your car to a mechanic. Regular maintenance like this can extend the life of your engine, ensure clean combustion and maximize fuel efficiency.

With the help of the Performance Tool spark plug change kit, you can tackle this job with confidence.