Heated Oxygen Sensor (HO2S) consists of zirconium and alumina
and is installed on upstream and downstream of the Manifold Catalyst
Converter (MCC).
After it compares oxygen consistency of the atmosphere with
the exhaust gas, it transfers the oxygen consistency of the exhaust gas
to the ECM. When the A/F radio is high or low, it generates
approximately 1V or 0V respectively. In order that this sensor normally
operates, the temperature of the sensor tip is higher than 370°C
(698°F). So it has a heater which is controlled by the ECM duty signal.
When the exhaust gas temperature is lower than the specified value, the heater warms the sensor tip.

Other information:
Replacement
1.
Discharge refrigerant from refrigeration system.
2.
Replace any faulty tubes or hoses.
Cap the open fittings immediately to keep moisture or dirt out of the system.
3.
Tighten the bolt or nut joint to the specified torque.
Th ...
Replacement
•
Put on gloves to prevent hand injuries.
•
When removing with a flat-tip screwdriver or remover, wrap protective tape around the tools to prevent damage to components.
•
When removing the interior trim pieces, use a p ...