How to Change a Lawn Mower Spark Plug

Spark plug and spark plug wrench.

What You’ll Need

To change the spark plug on your lawn mower, you will need the following.

1. Spark Plug

Lots of hardware stores sell spark plugs for lawn mowers, as well as agricultural supply stores, auto parts stores, home improvement centers, and lawn mower repair shops. If you bought your lawn mower at a big box store, check there first – they often carry parts for their stock lawn mowers.

To find the correct spark plug, consult your lawn mower owner’s manual. Or, take the old spark plug with you to the store, along with the make and model of your lawn mower. Most parts stores have a reference book where you can look up the part number and compare it with your old one.

2. Spark Plug Wrench

This handy tool makes changing your spark plug a snap. Or, I should say NOT a snap, because the purpose of the tool is to help prevent the ceramic plug body from breaking! Special spark plug sockets are also available for standard socket wrench sets.

3. Spark Plug Gap Gauge

This inexpensive small gauge is used to measure the gap in the spark plug where the spark is generated. If not adjusted correctly for the plug and mower, the spark plug will not spark. Check your lawn mower manual to find the correct distance.