Exhaust Gas (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 (amount of injection time) to obtain optimum combustion. Two types of oxygen sensor are used. The 4-cylinder models use a Zirconia oxygen sensor which produces a varying voltage signal relative to the oxygen content in the exhaust gases. The V6 models use a Titania oxygen sensor, which is a type of resistor.

The ECU provides the Titania oxygen sensor with a one-volt reference signal. Resistance of the ceramic Titania varies according to the exhaust gas conditions. A rich exhaust gas mixture causes sensor's resistance to drop, while a lean exhaust gas mixture causes resistance to increase. The ECU monitors the return signal from sensor and adjusts the air/fuel mixture according to this return signal. The sensor also contains an additional heating circuit to quickly bring sensor to operating temperature.