How to Find the Right Spark Plug for Your Lawn Mower

Remove the old spark plug from your lawn mower. Pull the spark plug wire off the plug, and remove the spark plug with a socket wrench. Stuff a rag into the spark plug hole in the engine. This prevents dirt and debris from getting into the combustion chamber.

Write down the brand and model number of your lawn mower. This information is usually on a metal plate somewhere on the mower deck. Also, write down the engine manufacturer and size as well. You most likely will not need all of this information, but it is better to have it on hand.

Go to the auto parts store or home improvement center. Look for the same manufacturer's plug first. If you find the same manufacturer, look for the same plug size as the current one. The plug size is printed on the side of the spark. The size is a series of letters and numbers.

Flip spark plug packages over if you do not see the same manufacturer as the old one. Read the back of the packages. Most spark plug packages indicate what size plug the one in the package is a good substitute for. This might be listed as the engine size, mower model or spark plug size.

Go to the small cross-reference booklet near the spark plugs. Most auto parts stores have a cross-reference book hanging on a shelf. Look for the manufacturer and size of your current spark plug. Once you find the original, look for the different substitute recommendations.

Ask the sales representative at the store if all other avenues still leave you without a replacement. Often the sales representative can look the spark plug size or mower information on a computer to find a quick replacement plug.