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 PCM. 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
PCM duty signal. When the exhaust gas temperature is lower than the
specified value, the heater warms the sensor tip.
