Where to Check the Spark Plug Model Number?
2 Answers
The model number of a spark plug can be found on its casing. Spark plugs are installed on the side or top of the engine. In earlier models, spark plugs were connected to the distributor via ignition cables, but over the past decade, most car engines have been updated to feature direct connections between the ignition coil and the spark plug. Main types of spark plugs include: Standard spark plugs, projected insulator spark plugs, electrode spark plugs, seat spark plugs, pole spark plugs, and surface gap spark plugs. How spark plugs work: The ground electrode of a spark plug is connected to the metal casing, which is then attached to the engine block via the cylinder head threads. The insulator primarily serves to isolate the metal casing from the central 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 central electrode, it ionizes the medium between the central electrode and the ground electrode, generating a spark that ignites the air-fuel mixture in the cylinder.
Open your car's glove compartment and check the manual. The vehicle maintenance manual has a dedicated section for part numbers, and the spark plug model is usually listed in the engine maintenance section or the parts list. Last time I helped a friend check the spark plugs for his Civic, I found the complete model number NGK IZFR6K11 in the table on page 87 of the manual. If you've lost the manual, don't panic—many cars have a technical parameters label on the inside of the front hood, which, in addition to tire pressure, often lists the spark plug heat range. There's also a simple but practical method: just remove the old spark plug and check—the full model code is laser-etched on the metal casing. When checking the model, remember to distinguish between the heat range and gap parameters. Japanese cars typically use a heat range of 6-7, while German cars prefer 7-8. Be careful not to buy the wrong model, as it could cause engine knocking.
