Downstream O2 Sensor Signal Inspection

1. Ignition "OFF".
2. Connect VMI to GDS and set up an oscilloscope as follow (4-channel);

   Channel A (+): Pin No. 3 (V_IP) terminal of Upstream O2 Sensor.

   Channel A (-): Ground

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

   Channel B (-): Ground

3. Ignition "ON" & Engine "ON".

   Courtesy of HYUNDAI MOTOR AMERICA

   1. Approx. 2500 RPM.
   2. Fuel Cut after acceleration.
   NOTE: If "B" area is abnormally long, it may be indication of aged Three-way Catalyst Converter.
4. Is the measured value within speechification?

YES 

• 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.

NO 

• Carefully re-do this troubleshooting guide steps.
• If no problems were found with the circuits or connectors, Replace the Three-Way Catalyst Converter and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.