Diagnostic Overview
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2010 BMW M6, 2010 BMW M5, 2009 BMW M6, 2009 BMW M5, and 2008 BMW M6. However, it is still accessible from the selected car via links, so may be relevant.
The fuel system monitoring is monitoring for permanent deviations of the A/F controller (lean and rich) from the mean position. After the enable conditions are met, a counter is started. At this point the ECM evaluates the total percentage of short and long term fuel control.