P2188 or P2190
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
The Long Term Fuel Trim Idle/Decel is less than -6 percent for 4 seconds, or for a cumulative of 30 seconds.