Rear Heated Oxygen Sensor

The rear heated oxygen sensor, after three way catalyst, monitors the oxygen level in the exhaust gas on each bank. Even if switching characteristics of the front heated oxygen sensor are shifted, the air fuel mixture is controlled to stoichiometric, by the signal from the rear heated oxygen sensor. The sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. Under normal conditions the rear heated oxygen sensor is not used for engine control operation.