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 DTC(s) 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.
- Ignition on, engine not running.
- With a scan tool, read DTCs.
Is the DTC active at this time?
Yes
- Go to step 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure
- 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.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure
No
- Go to step 3
- CHECKING THE EXHAUST SYSTEM FOR LEAKS
- Perform the diagnostic procedure for CHECKING THE EXHAUST SYSTEM FOR LEAKS. Refer to Non-DTC Diagnostics/Driveability - Gas - Diagnosis and Testing
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure
No
- Go to step 4
- Perform the diagnostic procedure for CHECKING THE EXHAUST SYSTEM FOR LEAKS. Refer to Non-DTC Diagnostics/Driveability - Gas - 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. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure
No
- Go to step 5
- Check the exhaust for excessive smoke caused by an internal problem in the engine.
- AGING O2 SENSOR
- A new rear O2 Sensor along with an aging front O2 Sensor may cause the DTC to set.
- Review the vehicles repair history.
Has the rear O2 Sensor been replaced without replacing the front O2 Sensor?
Yes
- Replace the Front O2 Sensor as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure
No
- Go to step 6
- CATALYTIC CONVERTER
If there are no possible cause remaining, view repair.
Repair
- Replace the Catalytic Converter.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure