Failing to replace spark plugs for an extended period will result in a significant decline in engine performance, primarily manifested as insufficient ignition energy, incomplete combustion, and unstable power output. Electrode wear and carbon deposit buildup can cause delayed ignition timing or misfires in spark plugs, leading to sluggish acceleration and increased fuel consumption (for instance, fuel consumption per 100 kilometres may rise from 7L to 9L). Concurrently, engine vibration and cold-start difficulties frequently occur. In severe cases, this may trigger a malfunction indicator light (MIL) warning, and even cause abnormal exhaust noise or engine stalling during operation due to multi-cylinder misfires, posing safety risks. Replacement intervals vary significantly among spark plugs of different materials: nickel alloy requires replacement every 20,000-30,000 kilometres, single platinum approximately 40,000 kilometres, double platinum 60,000 kilometres, while iridium and platinum-iridium can last 80,000 and 100,000 kilometres respectively. However, direct injection engines require shorter intervals of 20,000 kilometres due to their demanding operating conditions. Selecting OEM-specified models ensures optimal compatibility.
