Sub-Oxygen Sensor

DESCRIPTION
The Sub-Oxygen Sensor (Sub-O2S) is located in the exhaust system to detect the concentration of oxygen in the exhaust gases after these exhaust gases have passed through the Warm-Up Three Way Catalytic Converter (WU TWC). The Sub-O2S acts as an electrochemical cell or battery. A voltage is produced in response to the amount of oxygen in the exhaust stream compared to the oxygen content of the atmosphere.

OPERATION
A lean mixture (high O2 content in exhaust) will produce a low voltage. A rich mixture (low O2 content in exhaust) will produce a high voltage. Sub-025 voltage ranges from approximately 100 millivolts (0.1 volts) (high 02/lean mixture) to 900 millivolts (0.9 volts) (low 02/rich mixture).

By monitoring the voltage output of the Sub-02S, the ECM will determine what fuel mixture command to give to the injectors.

SENSOR CIRCUIT FAILURE
A failure in the Sub-02S circuit should set a DTC 27 Sub-Oxygen Sensor Circuit.