61 13 ... In-Line Plugs, 3-, 6-Pin, System Elo-Power 2.8
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 locking hook (1) in direction of arrow and disengage. Then unlock locking hook (2) and remove lock.
Press down arrester hook (1) with screwdriver and pull out cable with contact towards rear.