Parts for your 2020 Subaru Impreza-Thermostat housing

2020 Subaru Impreza thermostat-housing — what it does, and how to keep it sorted

Yes, the 2020 Subaru Impreza uses a thermostat housing. Technical references that confirm this include the Subaru Factory Service Manual for the 2017–2021 Impreza (Cooling section: Thermostat and Water Pump), which shows the thermostat fitted at the lower radiator hose position within the water pump cover, and Subaru’s official parts catalogue for the 2020 Impreza (Cooling System – Water Pump/Thermostat illustration), which lists the thermostat with an O-ring and a dedicated cover often described as the water inlet/thermostat cover. Trade databases such as ALLDATA and Mitchell 1 also depict the FB20 engine’s thermostat seated in a dedicated housing on the pump side of the engine.

On the 2020 Impreza’s FB20 engine, the thermostat-housing holds the thermostat in the correct position, directs coolant flow from the lower radiator hose, and seals the system with an O-ring. Its job is simple but crucial: help the engine warm up quickly, then regulate coolant flow so it stays in the sweet spot once up to temperature. A healthy housing keeps things leak-free and ensures the thermostat operates as designed.

There’s no fixed replacement interval for the housing itself