The Federal Standards pertaining to the exhaust emission control of the 1976 model year automobiles presumably demand the catalytic conversion of the pollutants involved. Provided the air-fuel ratio is maintained at a stoichiometric value, some problems (for instance, fuel economy) can be solved. A closed-loop system was developed, consisting of an electronic fuel injection system and a special oxygen sensor, called the λ-sensor, in the exhaust manifold.First results on vehicles indicate that this control system offers an promising solution to the reduction of harmful contaminants. The closed-loop system can be used with a three-way catalytic converter or with a dual-bed system. It has not yet been investigated whether the durability of the two systems is adequate, apart from the general problems of the durability of each catalyst.