19221-ZY9-H01 Impeller Housing - Overview. The 19221-ZY9-H01 Impeller Housing is an essential component in Honda marine engine systems, specifically supporting the water pump function within the cooling system. It serves as the enclosure for the impeller, guiding water flow efficiently to maintain optimal engine temperature and prevent overheating. Designed with precision to fit seamlessly within the water pump system, this impeller housing ensures reliable operation and long-term durability.. K