Conditions for Clearing the MIL/DTC

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The ECM turns OFF the MIL after three consecutive ignition cycles in which the diagnostic test runs and passes.
A scan tool can clear the MIL/DTC.
The ECM clears the DTC from ECM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
The ECM cancels the DTC default actions when the fault no longer exists and the DTC passes.