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 and ECM connector.
2. Measure resistance between terminal 1 of the HO2S harness connector and terminal 37 of the ECM harness connector.
3. Measure resistance between terminal 2 of the HO2S harness connector and terminal 42 of the ECM harness connector.

Fig 1: Measuring Resistance Between Terminal Of HO2S Harness Connector & Terminal Of ECM Harness Connector

Courtesy of HYUNDAI MOTOR CO.

• Specifications: below 1ohm 

Does each resistance indicate open? 

Yes: Go to next

No: Repair open 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.