Yeah mine did that exactly. It Didn't completely failed but was becoming more and more apparent. My Cuz opened the hood and took a look at it while i was Turnning the wheel left and right. Originally the groan wasn't that often or loud and only happened once in a while. but over a year span i believe it just got worse. Steering though i didnt notice any difference, except once when i did do a turn it locked and was very hard to turn. Had to brake turn off the car and restart before the steering wheel worked fine. Besides the Sound and that one incident i am not sure what other symptoms that can help determine if it is the Power Steering. Maybe someone here at the board can help more with that.

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2005 Black x5 3.0i