EGR Backpressure Transducer: Description and Operation

Back Pressure Transducer:

The back pressure transducer regulates the vacuum signal to the EGR valve. When the exhaust pressure is low, the transducer opens a small air bleed passage allowing some air into the vacuum circuit. This reduces the vacuum signal to the EGR valve and the valve closes slightly. If the exhaust pressure is very low the EGR valve will close completely. When exhaust pressure is high, the air bleed passage is closed and control vacuum is directly applied to the EGR valve diaphragm.