Clearing Diagnostic Trouble Codes

Description
The Powertrain Control Module (PCM) Reset allows the scan tool to command the PCM to clear all emission-related diagnostic information. When resetting the PCM, all of the On-board System Readiness (OSR) tests will be set to "not complete". To verify a repair or set the OSR tests to complete refer to Drive Cycles. For more information about a trip, refer to Trips and Drive Cycles.

The following events occur when a PCM reset is performed:
- Clears the number of Diagnostic Trouble Codes (DTC).
- Clears the freeze frame data.
- Clears oxygen sensor test data.
- Sets status of the OBD II system monitors to "not complete".

New Generation STAR Tester
- Turn key OFF.
- Perform the necessary vehicle preparation and visual inspection.
- Select VEHICLE & ENGINE SELECTION menu (OPTIONAL).
- Select SELECT NEW VEHICLE YEAR & MODEL.
- Select year, engine, model with the appropriate qualifier, if needed (i.e., transmission, 49 State, California) (OPTIONAL).
- Follow operating instructions from the menu.
- Select GENERIC OBD II FUNCTIONS.
- Press CONT button if all OBD II monitors are not complete.
- Turn key ON.
- Select CLEAR DIAGNOSTIC CODES.
- Press START key.
- Turn ignition key to the ON position or START vehicle (depending on the pinpoint/diagnostic manual instructions for the type of data requested).
- Verify tool is connected and communicating properly.
- Perform reset.
- When finished, turn ignition key to the OFF position.
- Disconnect scan tool from vehicle.

Resetting Keep Alive Memory (KAM)
Disconnect the negative lead from the battery for a minimum of 5 minutes (this will also result in the PCM Reset described above). Resetting KAM will also clear learned values the PCM has stored for adaptive systems such as idle and fuel. Once the vehicle is driven, the PCM will relearn new adaptive values. It will take a few miles and the vehicle may run rough until the values are relearned.