Oxygen Sensor

Sensor monitors the amount of unburned oxygen in the exhaust gases. When heated in the presence of exhaust gases, sensor provides a voltage signal which is used to adjust air/fuel mixture to obtain optimum combustion. Two types of oxygen sensor are used: heated (3-wires) and non-heated (one-wire). The heating circuit quickly brings sensor to operating temperature.

A rich exhaust gas mixture causes sensor voltage to drop; a lean exhaust gas mixture causes voltage to increase. The ECM monitors the return signal from sensor and adjusts the air/fuel mixture according to this return signal.