WARNING: This page is about a different car, the 2010 BMW X3, 2009 BMW X3, 2008 BMW X3, and 2007 BMW X3. However, it is still accessible from the selected car via links, so may be relevant.
ELECTRIC AUXILIARY HEATER - TIGHTENING TORQUES
Type
Thread
Tightening specification
Measure
1AZ Battery positive and negative leads to auxiliary heater