Refer to "Shop Manual" and viasullay and/or physically inspect following conditions;

- Exhaust System between O2 Sensor and Three-Way Catalyst Converter for air leakage, restriction and damage.

- Damage and for loose or missing hardware

Has any problems been found?

	▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
	▶ Go to "Three-Way Catalytic Converter Inspection" procedure.

Refer to "Shop Manual" and viasullay and/or physically inspect following conditions;

- Severe discoloration caused by excessive temperature.

- Dents and holes.

- Internal rattle caused by a damaged catalytic converter.

Has any problems been found?

	▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
	▶ Go to "O2 Sensor Inspection" procedure.

Ignition switch "OFF"

Connect VMI to GDS and set up an oscilloscope as follow (2-channel);

Channel A (+) : Pin No. 1 (Signal) terminal of Upstream O2 Sensor.

Channel A (-) : Ground

Channel B (+) : Pin No. 1 (Signal) terminal of Downstream O2 Sensor.

Channel B(-) : Ground

Ignition switch "ON" & Engine "ON"

Fig.1) Upstream O2 Sensor and Downstream O2 sensor Signal waveform (Warm-up Condition)

Is the measured value within specficiation?

▶ Fault might be intermittent and caused either by poor contact in connectors or wiring harness, or it has been repaired and control module memory is not cleared yet. Thoroughly check terminal of battery, all connectors(and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage. ▶ Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

▶ Carefully re-do this troubleshooting guide steps. ▶ If no problems were found with the circuits or connectors, Replace the Three-Way Catalytic Converter and then go to "Verification of Vehicle Repair" procedure.