Before just replacing the sway bar links, check to ensure that the nuts are tight. You'll need an 18mm thin open ended wrench to hold the ball joint side of the link. I forget the nut size other side. They do fail often, but sometimes they just loosen up.

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual