Let the engine cool completely
Locate the spark plugs
Remove the spark plug wire or ignition coil
Clean around the plug area
Remove the spark plug with the correct socket
Inspect the electrode and insulator
Check for carbon buildup
Check for oil or fuel fouling
Check for cracks or damage
Check the gap with a feeler gauge
Compare the plug condition to the manufacturer’s specifications
Replace worn or damaged plugs
Reinstall the spark plug and tighten to the correct torque
Reconnect the wire or ignition coil