Front Heated Oxygen Sensor

FRONT HEATED OXYGEN SENSOR (FRONT O2S)
The front O2S is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The sensor has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1 volt in richer conditions to 0V in leaner conditions. The sensor signal is sent to the Engine Control Module (ECM). The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1 volt to 0 volts.