31916-ZY9-H01 S/PLG (ZFR6K-9E) - Overview. The 31916-ZY9-H01 S/PLG (ZFR6K-9E) is a genuine Honda spark plug designed for the ignition system of Honda marine engines. Its primary role is to ignite the fuel-air mixture within the engine cylinders, ensuring efficient combustion and reliable engine operation. This spark plug supports Honda marine engine systems by delivering optimized ignition performance, helping maintain smooth engine function and fuel efficiency. Engineered to meet strict factory