Abstract: An electrically operated air pump for supplying air to the exhaust system of an internal combustion engine having a central mounting plate which is integral with the electric motor assembly. The armature shaft of the electric motor drives an impeller within a working chamber defined by an impeller housing and one side of the mounting plate. A silencer housing encloses the motor assembly and contains an air circuit for channeling air to and from the working chamber of the pump. The air circuit contains a solenoid operated air valve for restriction of outlet air, and sound insulation means for external sound reduction. The central mounting plate, impeller, impeller housing, and silencer housing are constructed of a polymeric material which allows complex features to be molded into the part thereby minimizing machining and assembly complexity.