Inspection Procedures

1. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

   Are all connectors good? 

Yes: Go to next

No: Repair or replace it.

1. Turn ignition switch to OFF position and disconnect HO2S connector.
2. Turn ignition switch to ON position.
3. Measure voltage of HO2S signal harness between terminal 2 of the HO2S harness connector and chassis ground.

Fig 1: Measuring Voltage Of HO2S Signal Harness Between Terminal 2 Of HO2S Harness Connector & Chassis Ground

Courtesy of HYUNDAI MOTOR CO.

• Specification: below 0.5V 

Is voltage within specification? 

Yes: Go to next

No: Repair short to power in harness.

1. Reconnect the HO2S and ECM connectors.
2. Warm up the engine to normal operating temperature.
3. Using a Hi-Scan (Pro), monitor the HO2S signal waveform.

Do the rear HO2S signals fluctuate between 0V and 1V? 

Yes: Proceed with ECM PROBLEM PROCEDURE  .

No: Replace HO2S.