EGR Backpressure Transducer: Description and Operation

The EGR back pressure variable transducer modulates the EGR vacuum so that the amount of gas flow is proportional to throttle opening. It does this by sensing the exhaust back pressure and bleeding off some of the vacuum when back pressure is low. Since exhaust pressure depends on engine load, it is the equivalent of a throttle opening signal. The EGR back pressure variable transducer is mounted just below the EGR valve.