1. Check For Short To Power In Harness

1. Turn ignition switch to OFF position and disconnect HO2S and ECM connectors.
2. Turn ignition switch to ON position.
3. Measure voltage between terminal 1 of the HO2S harness connector and chassis ground.
4. Measure resistance between terminal 2 of the HO2S harness connector and chassis ground.
5. Measure resistance between terminal 3 of the HO2S harness connector and chassis ground.
6. Measure resistance between terminal 4 of the HO2S harness connector and chassis ground.
   Fig 1: Measuring HO2S Harness Resistance

   Courtesy of HYUNDAI MOTOR CO.
   • Specifications: below 0.5V 

Is voltage within specification? 

Yes: Go to next step.

No: Repair short to power in harness.