12209-422-005 Valve Stem Seal - Overview. The 12209-422-005 Valve Stem Seal is a vital component within Honda marine engine systems. It supports the camshaft and valve system by preventing oil from leaking into the combustion chamber via the valve stem, which is crucial for maintaining engine lubrication and optimal performance. This OEM valve stem seal meets exact factory specifications and dimensions, providing a perfect fit for seamless integration with existing engine hardware and seals, ens