Repair procedures: Removal

Turn the ignition switch OFF and disconnect the battery negative (-) cable.
Disconnect the engine coolant temperature sensor connector (A).
Remove the sensor (B).

Fig 1: Identifying Engine Coolant Temperature Sensor Connector
Courtesy of HYUNDAI MOTOR AMERICA

CAUTION: Note that engine coolant may be flowed out from the water temperature control assembly when removing the sensor.
Supplement the engine coolant (Refer to "ENGINE COOLING SYSTEM " in EM group).