61 13 ... In-Line Plugs, 6-, 8-Pin, System MQS
WARNING: This page is about a different car, the 2007 BMW 550i and 2006 BMW 550i. However, it is still accessible from the selected car via links, so may be relevant.
Press lock (1) in direction of arrow and slide plug forward.
Press locking hook (2) downward and slide lock (1) out.
Press down arrester hook (1) with screwdriver and pull out cable with contact towards rear.