12209-GB4-682 Valve Stem Seal - Overview. The 12209-GB4-682 Valve Stem Seal is a critical component in Honda marine engine systems. It plays an essential role in preventing oil from entering the combustion chamber via the valve stem guides, which is vital for ensuring efficient engine operation and reduced emissions. This part is engineered to fit precisely within the Honda active marine valve system, ensuring seamless integration with existing parts, maintaining optimal performance and durabili