I've looked thru the boards and read all I could find re: power steering issues and can find no posts stating the symptoms I'm experiencing.The issue has been creeping in over weeks on my '09 Sport SC. I thought I heard/ felt something. I've been hearing a faint whine for quite some time - thought it could be normal supercharger noise. I'd feel ....something when backing out of my garage and turning 90deg - obviously at low/no speed. Then yesterday, backing out of a parking space and turning the wheel to lock, I felt substantial thumping/pulsing as if the ABS was engaged. Yet driving at even low speed (20mph & up) everything feels and functions as normal. Had to park it last nite so I haven't checked the PS fluid level but I'll bet it's full as I have never had any spotting on my garage floor.
Before I pay my dealer for a diagnosis, does this sound familiar to anyone?

 

I'm not sure if this translates to a '09 Sport, but on a '97 D1 the very same thing happened to me. In fact, I lost all braking power whilst performing a slow Uturn. The curb stopped me.

New ABS sensors fixed it.