Conditions for Clearing the MIL/DTC

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
A scan tool can clear the MIL/DTC.
The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM.

DTC P0120 (2.2L)

Step	Action	Yes	No
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Install a scan tool. Turn ON the ignition with the engine OFF. IMPORTANT: Before clearing the DTC, use the scan tool in order to record the ECM Freeze Frame and the TCM Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the ECM and the TCM. Using the Clear Info function erases stored DTCs in both the ECM and TCM. Record the DTC Failure Records. Did you record any ECM Failure Records?	Go to Diagnostic Trouble Code (DTC) List - Vehicle	Go to Step 3
3	Clear the DTC. Turn the ignition OFF for at least 30 seconds. Start the engine and allow it to idle. Did DTC P0120 set again?	Go to Step 4	Go to Testing for Intermittent Conditions and Poor Connections
4	Did any other DTCs set?	Go to Diagnostic Trouble Code (DTC) List - Vehicle	Go to Step 5
5	Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Is the action complete?	Go to Step 6	-
6	Perform the following operation to verify the repair: Select DTC on the scan tool. Select Clear Info. Start the engine and allow it to idle. Select Specific DTC. Enter DTC P0120. Has the test run and passed?	Go to Step 7	Go to Step 2
7	With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed?	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK