Computers and Control Systems: Description and Operation

Fig.20 - Closed Loop Feedback System:

The oxygen sensor feedback system, Fig. 20, is a self-tuning engine control system designed to reduce emissions. The oxygen sensor monitors the composition of the exhaust gases leaving the engine.

Signals from the oxygen sensor are transmitted into a closed loop feedback system, which continuously adjusts the air/fuel ratio to reduce emission of hydrocarbon (HC), carbon monoxide (CO) and nitrous gases (NOx). At high engine temperatures, an electrical current is built up and transmitted to the electronic control module (ECM).