Why are oxygen sensors used on all cars today?
	In the early 1970s the EPA enacted air pollution regulations aimed at improving our air quality. To comply with these regulations, and the demands of the motoring public, automakers in North America, Europe and Japan developed engine control systems that reduce exhaust gas emissions, improve fuel economy and provide good engine performance. In 1973 the initial zirconia oxygen sensor was developed, making the development of the closed loop engine control system possible.. The closed loop engine control system is used by every automaker today.
	How does an Oxygen sensor generate a voltage signal?
				Sensors are placed in the exhaust system where a constant flow of exhaust gas flows across the outer electrode while the inner electrode is exposed to outside air. When the sensor is heated to over 600oF the ceramic thimble begins to conduct oxygen ions between the electrodes. The flow of oxygen ions from the inner to the outer electrode creates an electrical voltage
	How are oxygen sensors used in the engine management system?
	The closed loop system consists of an engine control computer, fuel delivery system, oxygen sensor and a catalytic converter. Oxygen sensors are placed in the exhaust stream to determine the content of oxygen in the exhaust gases. The voltage signal generated by the O2 sensor is sent to the ECM. Based on these input signals the ECM controls the amount of fuel entering the engine keeping the engine in the optimum operating range.