P0140 or P0160
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the HO2S 2 voltage is between 410-490 mV for at least 74 s.