2000-2002 G20 Mil ON Rear O2 Sensor DTC

If a 2000 to 2002 G20 has a MIL "On" and any of the following DTCs stored in the ECM:
• P0138 Heated Oxygen Sensor 2 (Rear) (Bank 1) (Max. Voltage Monitoring)
• P0139 Heated Oxygen Sensor 2 (Rear) (Bank 1) (Response Monitoring)
• P0140 Heated Oxygen Sensor 2 (Rear) (Bank 1) (High Voltage)
Start with the Service Procedure to find out if the bulletin applies to this vehicle. If it does apply, complete the Service Procedure to repair the incident, if it should occur.
SERVICE PROCEDURE
You will be performing the following, as required:
• Determine the DTC Stored in ECM from the CONSULT-II Self-diagnosis results.
• ECM Part Number Check to determine if this bulletin applies.
• ECM Reprogramming (required if the ECM P/N in the vehicle matches one of those listed under “Current ECM P/N” in Chart A -page 2).
• Replacing the Rear Oxygen Sensor (required if ECM Reprogramming is needed).
Determine the DTC Stored in ECM:
1. Determine which DTC code is stored in the vehicle's ECM by performing CONSULT-II Self-Diagnosis.
2. Print out the Self-Diagnosis results for use in ECM Part Number Check, below. See Figure 1 for an
example of the CONSULT-II Self-Diagnosis printout.

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