Oxygen (O2) Sensor

The oxygen sensor is located on top of the exhaust manifold, just ahead of the tailpipe connection or turbo outlet (turbo models), so that it is exposed to exhaust. The sensor is electrically heated internally for faster switching when engine is running. Its function is to monitor the oxygen content of the exhaust, and to supply the SMEC with a voltage signal which is directly proportional to amount of oxygen in the exhaust.

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

In this manner, the SMEC 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 under any given condition.