CMP Actuator System Performance Diagnostics
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The PCM monitors the performance of the CMP Actuator system by monitoring the actual and desired positions of a cam phaser. If the difference between the actual and desired position is more than a calibrated angle for more than a calibrated amount of time, a DTC will set.