[Bank 1/Sensor 1]

Turn the ignition switch OFF and disconnect the battery negative (-) cable.
Disconnect the connector (A), and then remove the sensor (B).
Information

Note that the SST (Part No.: 09392-1Y100 or 09392-2H100) is useful when removing the heated oxygen sensor.

Fig 1: Identifying Heated Oxygen Sensor Connector (Bank 1/Sensor 1)
Courtesy of HYUNDAI MOTOR AMERICA

Fig 2: Identifying Heated Oxygen Sensor (Bank 1/Sensor 1)
Courtesy of HYUNDAI MOTOR AMERICA