If a crack were to form or a seam were to separate in the heater core end piece, hot coolant could suddenly be expelled, increasing the risk of personal injury to a vehicle occupant.
Vehicle description: Passenger vehicles. A malfunction or failure of a coolant system component, such as a thermostat, water pump, or fan belt, can result in significantly increased coolant temperature and system pressure. If the indications of a critical overheating condition is not noticed by the driver, it is possible that damage to, or failure of, a coolant system component could occur.