Conditions For Clearing MIL/DTC

WARNING: This page is about a different car, the 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.

The MIL will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up cycles without a fault.
All DTC Information can be cleared using a scan tool.
Interruption of AF ECM or PCM power or ground may clear DTC Information. Clearing DTC Information with this method is inconsistent and should not be performed.