Conditions For Clearing MIL/DTC

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

The control module will turn OFF the MIL during the third consecutive trip in which the diagnostic ran and passed.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
The History DTC will clear after 40 consecutive warm-up cycles without a malfunction.
The DTC can be cleared with a scan tool.