Conditions For Clearing MIL/DTC

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

PCM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and passes.
A History DTC clears after 40 consecutive warm-up cycles in which there are no failures reported of this diagnostic or any other emission related diagnostic.
The scan tool clears the MIL/DTC.