Conditions for Setting the DTC: P013A
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the accumulated mass air flow monitored during rich-to-lean transitions between 450-150 mV is more than 75 grams.