Inspection Procedures

1. Check connectors for poor connection, misplaced, bent, loose or corroded terminals.

Are both connectors good? 

Yes: Go to next step.

No: Repair or replace HO2S

1. Disconnect HO2S connector.
2. Measure resistance between the terminals 3 and 4 of HO2S connector.

Fig 1: Measuring Resistance Between Terminals 3 & 4 Of HO2S Connector

Courtesy of HYUNDAI MOTOR CO.

• 3 ~ 4 Ω at between 18°C and 28°C (64°F ~ 82°F) 

Is resistance within specification? 

Yes: Go to next step.

No: Replace HO2S.

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

Fig 2: Measuring Voltage Between Terminal 3 Of HO2S Harness Connector & Chassis Ground

Courtesy of HYUNDAI MOTOR CO.

• Specification: approximately B+ 

Is voltage within specification? 

Yes: Go to next step.

No: Repair open or short to ground in harness.

1. Warm up engine to normal operating temperature.
2. Using Hi-Scan (Pro), monitor the signal.

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

Yes: Proceed with ECM PROBLEM PROCEDURE .

No: Replace HO2S