Spectrol Electronics, Inc. (www.spectrol.com) is manufacturing exhaust gas recirculation (EGR) valve position sensors (EVP). An EVP is mounted on the vacuum actuator of the EGR valve which, in turn, is mounted on the intake manifold. The EGR valve recirculates exhaust gas into the intake manifold to help control oxides of nitrogen. By sensing the position of the valve at any instant, the EVP can signal the engine control computer to aid in adjusting various engine parameters. It is essentially a linear potentiometer whose voltage output signal is proportional to the displacement of the input plunger. This basic technology is currently being used for hydraulic and electrically operated actuators.