Oxygen Sensor

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

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

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

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