To determine whether spark plugs need replacement, a comprehensive assessment can be made from multiple aspects. First is the visual inspection: a normal spark plug should be tan or rust-colored with a smooth surface free of carbon deposits; if it appears blackened, has severe carbon buildup, or shows electrode erosion, replacement is required. The electrode gap should be maintained within 0.6 to 1.3 millimeters; measurement with a caliper beyond this range indicates excessive wear. Symptoms including hard cold starts (cranking duration exceeding 5 seconds), abnormal engine vibration at idle, sluggish acceleration (particularly delayed throttle response during uphill driving), abnormally increased fuel consumption (resulting from incomplete combustion requiring additional fuel injection), and black exhaust smoke all indicate deteriorating spark plug performance. Additionally, engine knocking noises or unexpected stalling while driving may signal spark plug failure. Regarding service life: standard copper-core spark plugs should be replaced every 30,000 kilometres, while platinum and iridium variants can last 60,000 and 80,000 kilometres respectively. However, inspection is recommended after 4 years of use regardless of mileage. When multiple symptoms manifest concurrently, immediate replacement is advised to prevent engine damage, with OEM-specified models being preferable to ensure compatibility.
