31916-ZY3-004 S/PLG (VKJ20RZ-M11) - Overview. The 31916-ZY3-004 S/PLG (VKJ20RZ-M11) is a genuine OEM spark plug designed specifically for Honda marine engine systems. This spark plug plays a critical role in igniting the air-fuel mixture within the engine, ensuring reliable starts, consistent power output, and optimal fuel efficiency. Engineered to meet precise factory specifications and tolerances, it ensures seamless integration with existing parts, maintaining optimal performance and durabili