Conditions for Setting the DTC
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
This DTC is set when the height sensor detects the exhaust valve has been on for 255 seconds and the height sensor did not detect the calibrated downward movement.