What happens when Subaru Forester has no power steering fluid?

Since the pump uses the fluid for lubrication and cooling, running without fluid will quickly wear and destroy the pump. However, when it runs low you will notice the steering getting tight right away and probably caught it in time to keep from doing any real damage. But you do need to get the problem fixed before it drains down again. It is likely that you will just need a new hose. Any garage can do this for you.