BMW of North America (BMW) is recalling certain model year 2011 BMW 528i, 528xi, 535i, 535xi, 550i and 550xi vehicles manufactured March 1, 2010, through August 31, 2011. The affected vehicles may have received a replacement Sensor Cluster Unit (SCU) during a service visit. These SCUs have an acceleration sensor that may have been incorrectly programmed and, as a result, the SCU may not accurately determine if activation and deployment of the air bags, safety belt pre-tensioners and head restraints is necessary in the event of a crash.