Step 1.

Connect the ignition tester to the lawn mower. Insert the metal portion into the socket of the spark plug boot. Connect the rubber portion to the spark plug.

Step 2

With the ignition tester connected, pull the start cord multiple times and observe for the light on the ignition tester to turn on.

Step 3

If the light on the ignition tester turns on, the problem with your lawn mower is most likely the spark plug – you need to replace it (assuming your lawn mower doesn’t start). If the light doesn’t turn on, then the problem is in either the ignition cable or the ignition coil itself.