Conditions for Setting the DTC: P0068
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the throttle position and the indicated engine load do not correspond with the expected load and throttle position for less than 1 second.