What are the functions and roles of automotive spark plugs?

[McBeau]

The functions and roles of spark plugs: The ground electrode of the spark plug is connected to the metal shell, which is attached to the engine block via the cylinder head threads. The insulator primarily serves to isolate the metal shell from the center electrode. The terminal nut is the part of the spark plug that contacts the high-voltage coil. When current passes through the terminal nut and the center electrode, it ionizes the medium between the center electrode and the ground electrode to generate a spark, thereby igniting the air-fuel mixture in the cylinder. Spark plug replacement intervals: Under normal maintenance conditions, spark plugs should be replaced every 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it is recommended to follow the user manual. The following standards can be referenced for maintenance and replacement: Platinum spark plugs should be replaced at 40,000 kilometers, ordinary nickel alloy spark plugs at 20,000 kilometers, and iridium spark plugs at 60,000 to 80,000 kilometers.