How to Change Spark Plugs

by Contributor

Old and worn spark plugs can result in your engine misfiring, lower performance and, even worse, low gas mileage. It is recommended that you change your car's spark plugs at 100,000 miles. Changing the spark plugs at the first sign of trouble can save you a lot of problems in the long run.

Wait until the car engine is cold. You should not perform any maintenance while the car is hot from use, especially on hot, electrical items like spark plugs.

Remove one spark plug wire from the plug. If you do this by hand, grab it by the plug boot. Don't pull on the wire. Use a spark plug wire puller to remove the spark plug so you don't rip the wire.

Clean away any dirt and debris from the spark plug hole. This can be wiped away, but blowing it off with compressed air works even better.

Remove the plug with a socket or ratchet wrench. Make sure you have the right size for your plugs, usually a 13/16 inch or 5/8 inch wrench. And, you may need an extension, too. Turn the plug counter-clockwise to remove it.

Put the new spark plug in. Twist it clockwise by hand first, then tighten it with the same wrench. Connect the wire back in place; it should snap on to tell you it's connected.

Repeat the process to change the remaining spark plugs. It's best to change them one at a time to keep things in order and avoid mixing up plugs and wires.


  • check Be sure to read the car manual and any other service book you can find on your model. You want to know everything about the car engine before starting any do-it-yourself maintenance.

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