Oxygen Sensor (O2S)

O2S sensor produces a small electrical voltage (0-1 volt) when exposed to oxygen in exhaust gas flow. O2S sensor is electrically heated for faster switching. Heating element is powered through Auto Shutdown (ASD) relay.

O2S sensor acts like a rich/lean (air/fuel ratio) switch by monitoring oxygen content in exhaust gas. This information is used by PCM to adjust air/fuel ratio by adjusting injector pulse width.

O2S sensor produces low voltage when oxygen content in exhaust gas is high. When oxygen content in exhaust gas is low, O2S sensor produces a higher voltage.