Conditions for Setting the DTC: P2125
WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The APP sensor 2 voltage is less than 0.325 volt, or more than 4.75 volts for more than 0.4 second.