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 terminals 1 and 2 of the HO2S.
3. Measure resistance between terminal 2 of the HO2S and chassis ground.

Fig 1: Measuring Resistance Between Terminal 2 Of HO2S & Chassis Ground

Courtesy of HYUNDAI MOTOR CO.

• Specifications: infinite 

Does each resistance indicate open? 

Yes: Go to next

No: Repair short or short to chassis ground 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.

   Is the rear HO2S signal normal? 

Yes: Proceed with ECM PROBLEM PROCEDURE  .

No: Replace HO2S.