Conditions For Clearing MIL/DTC

WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

The PCM will turn the Malfunction Indicator Light (MIL) OFF during the first consecutive trip in which the diagnostic has been run and passed.
A last test failed (current DTC) clears when the PCM turns OFF the MIL.
The history DTC will clear after the PCM runs and passes 40 consecutive warm up cycles with no failure.
The DTC can be cleared by using a scan tool.