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How to Replace the Spark Plugs on a 1999 Buick Century

by Gregory Crews

Replacing the spark plugs in a 1999 Buick Century can be a tricky task because, while the front three are easy to get to, the back three spark plugs are not easy to access and you may need to use a stepladder to reach them. Replacing spark plugs can help increase fuel economy and engine performance.

Open the hood to access the engine compartment. Locate the sparkplug wires in the front of the engine. The wires can be traced from the coil pack mounted behind the engine. Follow the bright orange wire to the front of the engine that is plugged in to the engine cylinder.

Pull the sparkplug wire by gently twisting and pulling it out. This will expose the sparkplug.

Unscrew the sparkplug by placing a 5/8" deep well socket attached to the socket wrench over the sparkplug and unscrewing it from the engine cylinder.

Replace with the new sparkplug. Insert the new sparkplug and screw it in by hand. Tighten the sparkplug with a socket wrench to ensure it is tight.

Push the sparkplug wire on to the end of the sparkplug and push. The wire will lock in place.

Repeat steps to replace each spark plug. You may need to stand on a step ladder to reach the back three spark plugs.


  • Always change sparkplugs one at a time to ensure the sparkplug wires are plugged in to the correct cylinder.


  • Ensure the car is turned off and the keys are out of the ignition.

Items you will need

About the Author

Gregory Crews has been in the film industry for three years and has appeared in more than 38 major motion pictures and 16 television shows. He also writes detailed automotive tutorials. His expertise in the automotive industry has given him the skills to write detailed technical instructional articles.

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