Oxygen Sensor

The oxygen (O2) sensor is mounted in the exhaust manifold where it is exposed to exhaust gas flow. Its function is to monitor oxygen content of exhaust gases and to supply the ECU with a voltage signal directly proportional to this content.

If the oxygen content of exhaust gases is high (lean air/fuel mixture), the voltage signal to the ECU is low. As oxygen content decreases (mixture becomes richer), signal voltage increases.

In this way, the ECU is kept constantly informed of air/fuel ratio. It can then alter fuel injector "on" time, in response to these signals, to obtain the best air/fuel ratio of 14.7:1 under any given operating conditions.

The O2 sensor is equipped with a heating element that keeps the sensor at proper operating temperatures. Maintaining correct sensor temperatures at all times guarantees a more accurate signal to the ECU. By using an O2 heater, the fuel control system may also enter the "closed loop" operating mode sooner and maintain this mode, even during periods of extended idle.