Home Tips & Tricks How to Bench Test a Spark Plug

How to Bench Test a Spark Plug


At its most basic level, a spark plug is a device that starts your engine. The spark created by the plug when the key is turned on, ignites a mixture of fuel and air which gets the engine going. Bad spark plugs will prevent the engine from starting. You can bench-test each spark plug to help identify any that are malfunctioning. If the spark plugs are found to be in good working order, the problem may be the ignition instead.

Things You’ll Need

Spark plug tester


  • Turn off the car and open the hood. Disconnect the spark plug wire from the spark plug.