The frequency for changing spark plugs varies widely depending on the type and quality of the spark plugs, as well as the vehicle make and model. Generally, spark plugs should be replaced every 20,000 to 150,000 miles. For many modern vehicles, the typical replacement interval falls between 30,000 and 90,000 miles, with some specific models like the Toyota Corolla requiring replacement around 60,000 miles, and others like the Toyota Sienna up to 120,000 miles
. Key signs that spark plugs need replacement include rough idling, slow acceleration, hard starting, a check engine light, and poor fuel economy. These symptoms indicate the plugs are worn and not igniting the fuel-air mixture efficiently, which can affect engine performance and emissions
. For best results, consult your vehicle’s owner manual for the manufacturer’s recommended interval, as it is tailored to your specific car. If unsure or if experiencing symptoms of worn spark plugs, having them inspected and replaced by a mechanic is advisable
