Oxygen (O2) Sensor

O2 sensor is mounted in exhaust manifold, where it is exposed to hot exhaust gas flow. O2 sensor monitors oxygen content of exhaust gases and generates voltage signals directly proportional to oxygen content. This signal is continuously being supplied to logic module when vehicle is running.

Voltage signal to logic module is low when oxygen content of exhaust gases is high, indicating lean air/fuel mixture. If oxygen content decreases (mixture becomes richer), signal voltage will increase.

Using this information, logic module will alter fuel injector pulse duration (dwell) to obtain best air/fuel ratio for any given operating condition.