I have a 2007 STS and the power steering stopped working it was intermitent but now it does not work at all. I was told it could be the power steering actuator whats that. I flushed the power steering fluid twice ( It was dirty) but it still will not work. There are no strange noises never was when you first start the car it seems like its going to work but 15 seconds later the service steering light comes on and it just won't work any ideas please.