Power Circuit Inspection

Ignition "OFF".
Disconnect HO2S connector.
Ignition "ON" & Engine "OFF".
Measure voltage between Heater Power terminal of the HO2S harness connector and chassis ground.
Specification: B+

Fig 1: Oxygen Sensor (UP) - Circuit Diagram
Courtesy of HYUNDAI MOTOR AMERICA
Is voltage display near the specified value?
YES
- Go to "CONTROL CIRCUIT INSPECTION " procedure.
NO
- Check for open or short in the power supply circuit between the main relay and the HO2S.
  Especially check for "15A Sensor 2 fuse" is installed and not blown.
  
  Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
  
  NOTE: HO2S must have a clean air reference to function properly. The air is obtained by way of the sensor wire(s). Do not attempt to repair the wire(s), connector, or the terminals.