Diagnostic Test
- ACTIVE DTC NOTE:
A new rear O2 Sensor along with an aging front O2 Sensor may cause the DTC to set. Review the repair history of the vehicle before continuing.
NOTE:If an O2 Sensor DTC set along with the Catalytic Converter Efficiency DTC diagnose the O2 Sensor DTCs before continuing.
NOTE:Check for contaminants that may have damaged the O2 Sensor and Catalytic Converter: contaminated fuel, unapproved silicone, oil and coolant, repair necessary.
- Start the engine.
- Allow the engine to reach normal operating temperature.
- With the scan tool, read DTCs.NOTE:
It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.
Is the DTC Active or Pending at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
- VISUALLY INSPECT CATALYTIC CONVERTER
- Inspect the Catalytic Converter for the following damage:
- Damage Catalytic Converter, dents or holes.
- Severe discoloration caused by overheating the Catalytic Converter.
- Catalytic Converter broke internally.
- Inspect both ends of the converter, inlet and outlet.
- Leaking Catalytic Converter.
Were any problems found?
Yes
- Replace the Catalytic Converter. Repair the condition that may have caused the failure. Refer to CONVERTER, CATALYTIC, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 3
- Inspect the Catalytic Converter for the following damage:
- CHECK THE (K902) O2 SENSOR 2/1 RETURN CIRCUIT VOLTAGE
- CHECK THE (K904) O2 SENSOR 2/2 RETURN CIRCUIT VOLTAGE
- CHECK THE (K902) O2 SENSOR 2/1 RETURN CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Disconnect the PCM C2 harness connector.
- Measure the resistance between ground and the (K902) O2 Sensor 2/1 Return circuit in the O2 Sensor 2/1 harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 6
No
- Repair the (K902) O2 Sensor 2/1 Return circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK THE (K902) O2 SENSOR 2/1 RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE CAUTION:
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.
- Connect the (special tool #10436, Adapter, GPEC Diagnostic).
- Measure the resistance of the (K902) O2 Sensor 2/1 Return circuit from the O2 Sensor 2/1 harness connector to the GPEC Adaptor.
Is the resistance below 5.0 Ohms?
Yes
- Go To 9
No
- Repair the (K902) O2 Return Upstream circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK THE (K904) O2 SENSOR 2/2 RETURN CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Disconnect the O2 Sensor 2/2 harness connector.
- Measure the resistance between ground and the (K904) O2 Sensor 2/2 Return circuit in the O2 Sensor 2/2 harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 8
No
- Repair the (K904) O2 Sensor 2/2 Return circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK THE (K904) O2 SENSOR 2/2 RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE CAUTION:
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.
- Connect the (special tool #10436, Adapter, GPEC Diagnostic).
- Measure the resistance of the (K904) O2 Sensor 2/2 Return circuit from the O2 Sensor 2/2 harness connector to the GPEC Adaptor.
Is the resistance below 5.0 Ohms?
Yes
- Go To 9
No
- Repair the (K904) O2 Sensor 2/2 Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- POWERTRAIN CONTROL MODULE (PCM)
- Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Sensor and the Powertrain Control Module (PCM).
- Look for any chafed, pierced, pinched or partially broken wires.
- Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and the Powertrain Control Module connectors.
- Perform any Technical Service Bulletins that may apply.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Replace and program the Powertrain Control Module in accordance with the service information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Sensor and the Powertrain Control Module (PCM).
- CHECKING THE EXHAUST SYSTEM FOR LEAKS
- Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS test procedure. Refer to DIAGNOSIS AND TESTING
.
Were any exhaust leaks found?
Yes
- Repair or replace the leaking exhaust parts as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 11
- Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS test procedure. Refer to DIAGNOSIS AND TESTING
.
- ENGINE MECHANICAL CONDITION
- Check the exhaust for excessive smoke caused by an internal problem in the engine.
Is an engine mechanical condition present?
Yes
- Repair the engine mechanical condition as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 12
- Check the exhaust for excessive smoke caused by an internal problem in the engine.
- AGING O2 SENSOR
- A new Downstream O2 Sensor along with an aging Upstream O2 Sensor may cause the DTC to set.
- Review the vehicles repair history.
Has the Downstream O2 Sensor been replaced without replacing the Upstream O2 Sensor?
Yes
- Replace the front O2 Sensor as necessary. Refer to REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 13
- CATALYTIC CONVERTER
If there are no possible cause remaining, view repair.
Repair
- Replace the Catalytic Converter. Refer to CONVERTER, CATALYTIC, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .