Heated Oxygen Sensor (HO2S) consists of the zirconium and the
alumina and is installed on upstream and downstream of the Warm-up
Catalytic Converter (WCC).
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 A/F ratio is rich or lean, 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.
Inspection
1.
Ignition "OFF".
2.
Disconnect the intake actuator connector.
3.
Verify that the actuator operates to the recirculation position when connecting 12V to the terminal 3 and grounding terminal 7.
4.
Verify that the intake actuator operates to the fresh position when connecting in the reverse.