Kia Optima: Heated Oxygen Sensor (HO2S). Description and OperationThe sensor must be hot in order to operate normally. To keep it hot, the sensor has a heater which is controlled by the ECM via a duty cycle signal. When the exhaust gas temperature is lower than the specified value, the heater warms the sensor tip.

Installation
Heated Oxygen Sensor (HO2S). SpecificationsAutomatic climate control system
Type A
Type B
1. Fan speed control switch 2. Driver’s temperature control knob 3. Outside
air position button 4. Air conditioning button 5. Front windshield defroster
button 6. Mode select ...
Manual transaxle
...
Inspection
1.
Turn the ignition switch OFF.
2.
Disconnect the CCV connector.
3.
Measure resistance between the CCV terminal 1 and
2.
4.
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