P013E or P014A
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 O2 sensor voltage has not decreased below 450 mV within 42 grams of accumulated air flow.