Where is the spark plug installed?

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The spark plug is 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 or so, most passenger car engines have been updated to feature direct connection between the ignition coil and the spark plug. How spark plugs work: The spark plug's ground electrode is connected to the metal shell, which is threaded into the engine block via the cylinder head. 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 center electrode, it ionizes the medium between the center electrode and ground electrode to create a spark, thereby igniting the air-fuel mixture in the cylinder. Spark plug replacement intervals: Under normal maintenance conditions, replacement is recommended every 40,000-60,000 kilometers. However, this may vary depending on the brand and engine type, so always consult your owner's manual. The following replacement standards may serve as reference: Platinum spark plugs: replace at 40,000 km; standard nickel alloy spark plugs: replace at 20,000 km; iridium spark plugs: replace at 60,000-80,000 km.