Diagnostic Trouble Code (DTC) Clearing
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
The Automatic Level Control diagnostic trouble codes will clear when the ignition switch has been transitioned from off to on and the conditions that caused the code to set have been removed.