Conditions For Clearing MIL/DTC

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The PCM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and does not fail.
A History DTC clears after 40 consecutive warm up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.
The scan tool clears the MIL/DTC.