EGR Backpressure Variable Transducer
The EGR backpressure variable transducer modulates EGR vacuum so amount of gas flow is in proportion to throttle opening. It does this by sensing exhaust backpressure and bleeding off some of the vacuum when backpressure is low. Since exhaust pressure depends on engine load, it is equivalent to throttle opening signal.
The EGR backpressure variable transducer is mounted just above the EGR valve.