Conditions For Clearing DTC

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

The PCM turns off the MIL after 3 consecutive ignition cycles that the diagnostic runs and passes.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A DTC stored in history clears after 40 warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Use the scan tool in order to clear the DTC.