Inspection Procedures

1. Connect Hi-Scan (Pro) to data link connector and warm up engine to normal operating temperature.
2. Using Hi-Scan (Pro), monitor HO2S signal.

Does the HO2S signal switch from lean to rich or from rich to lean? 

No: Go to next step.

Yes: Problem is intermittent or was repaired and engine control module memory was not cleared. Proceed with HOW TO COPE WITH INTERMITTENT MALFUNCTIONS .

1. Thoroughly check connectors for loose, poor connection, bent, corrosion, contamination, deterioration or damage.

Are all connectors good? 

Yes: Go to next step.

No: Repair or replace it.

1. Turn ignition switch to OFF and disconnect HO2S and ECM connectors.
2. Measure resistance between the terminals 1 and 2 of HO2S harness connector.
3. Measure resistance between the terminals 1 of HO2S harness connector and chassis ground.

Fig 1: Checking HO2S Harness

Courtesy of HYUNDAI MOTOR CO.

• Specifications: infinite 

Does each resistance indicate open? 

Yes: Go to next step.

No: Repair short or short to chassis ground in harness.

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

• Refer to  SIGNAL WAVEFORM   for more information. 

Does the HO2S signal switch from lean to rich or from rich to lean? 

Yes: Proceed with ECM PROBLEM PROCEDURE .

No: Replace HO2S.