Conditions for Setting the DTC: P2120
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The APP sensor 1 voltage is less than 0.46 V or greater than 4.7 V for greater than 0.2 s.