How to Check if Spark Plugs are Good or Bad?

[SanJasper]

Methods to check the condition of spark plugs: Observe the color of the spark plug—grayish-yellow indicates normal condition and no need for replacement. If the center electrode shows signs of corrosion, it indicates poor condition and requires replacement. After removal, install the spark plug wire and ground the side of the spark plug to observe the strength of the spark and whether it jumps at the center of the spark plug. Weak sparks or sparks jumping around the electrodes also indicate the need for replacement. The spark plug is a crucial component of a gasoline engine's ignition system. It introduces high voltage into the combustion chamber and creates a spark by jumping the electrode gap, thereby igniting the combustible air-fuel mixture in the cylinder. A spark plug mainly consists of a terminal nut, insulator, terminal stud, center electrode, side electrode, and shell, with the side electrode welded onto the shell.