How to Identify Spark Plug Model Numbers?

[DeWillow]

Spark plug model numbers can be viewed on their outer casing. Spark plugs are installed on the side or top of the engine. In early designs, they connected to the distributor via ignition cables, but over the past decade, most passenger car engines have adopted direct coil-on-plug configurations where ignition coils connect directly to spark plugs. Main types of spark plugs include: Standard spark plugs, extended insulator spark plugs, electrode spark plugs, seat-type spark plugs, pin-type spark plugs, and surface-gap spark plugs. Spark plug working principle: The ground electrode connects to the metal shell, which threads into the engine block via cylinder head. The insulator isolates the metal shell from the center electrode. The terminal nut contacts the high-voltage coil - when current flows through the terminal nut and center electrode, it ionizes the medium between the center and ground electrodes to generate sparks, thereby igniting the air-fuel mixture in the combustion chamber.