The oxygen sensor for automobiles is widely used for the exhaust gas control system by using a three way catalyst and constitutes a very important function part of combustion control system in the internal combustion engine. The air-fuel ratio is controlled at the stoichiometric point, where the best purification efficiency is obtained.Recently a wide range air-fuel ratio control system has been developed for the areas of lean burn combustion for fuel economy, low emissions at low temperature starts, and full power control at W.O.T. with rich burning. The UEGO (Universal Air-Fuel Ratio Heated Exhaust Gas Oxygen) sensor has been developed to meet the wide range of air-fuel ratio control. This UEGO sensor indicates output proportionally for all ranges of air-fuel ratio, unlike the conventional oxygen sensor which detects only the stoichiometric point.This paper details the lean burn sensor previously developed and the UEGO sensor, as well as their development process, construction, mechanism, characteristics and the control systems. It also offers comments on the advantages of the UEGO sensor for possible future applications.