What type of spark plug does the Corolla use?
2 Answers
The Corolla uses SC20HR11 iridium-platinum spark plugs. A spark plug mainly consists of a terminal nut, insulator, terminal stud, center electrode, side electrode, and shell. The main types of spark plugs include: standard spark plugs, projected insulator spark plugs, electrode-type spark plugs, seat-type spark plugs, pole-type spark plugs, and surface-gap spark plugs. Spark plugs are installed on the side or top of the engine. Early spark plugs were connected to the distributor via ignition cables, but over the past decade, most car engines have switched to direct connection between ignition coils and spark plugs. Under high voltage, the air between the center electrode and side electrode of the spark plug rapidly ionizes, forming positively charged ions and negatively charged free electrons. When the voltage between the electrodes reaches a certain level, the number of ions and electrons in the gas increases like an avalanche, causing the air to lose its insulating properties and forming a discharge channel, resulting in a "breakdown" phenomenon. At this point, the gas becomes a luminous body, known as a "spark." Along with thermal expansion, a "crackling" sound is also produced. The temperature of this electric spark can reach 2000-3000°C, which is sufficient to ignite the air-fuel mixture in the engine combustion chamber.
When it comes to the Corolla's spark plugs, I've been driving this car for several years and have replaced them several times. The factory-equipped ones are mostly Denso iridium spark plugs from Japan, with models like SK16 or SK20, which have a long lifespan, needing replacement only after about 100,000 kilometers. They provide quick engine ignition and lower fuel consumption. During my last maintenance, the mechanic mentioned that the Corolla's engine design is well-matched with this material, unlike ordinary copper plugs that are more prone to carbon buildup. For regular checks, just open the hood and inspect the color of the spark plugs; if they appear black, it indicates aging and the need for replacement. Remember not to skimp and use off-brand products—stick to factory or genuine Denso to ensure ignition efficiency, avoid engine jerking, and maintain smooth driving at high speeds.
