Circuit/System Testing

Engine idling, observe the DTC information with a scan tool. Verify there are no HO2S or misfire DTCs set.
- If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to diagnosis the applicable DTC, before proceeding with this diagnostic procedure.
Verify the following conditions do not exist with the catalytic converter:
- Dents
- A severe discoloration caused by excessive temperatures
- Road damage
- An internal rattle caused by damaged catalyst substrate
- Restrictions
- If a condition is found, replace the catalytic converter.
Verify the following conditions do not exist with the exhaust system:
- Leaks
- Physical damage
- Loose or missing hardware
- Properly torqued HO2S
- If a condition is found, repair the exhaust system.
Verify the following conditions do not exist with the HO2S 2:
- A grounded wiring harness
- Damage
- If a condition is found, replace the HO2S 2.
If no physical condition is detected and the HO2S 2 is as active as the HO2S 1 after operating the engine at 1,500 RPM for 1 minute and then returning to a stabilized idle, then replace the catalytic converter.