Yes, absolutely, your vehicle will fail the smog check with the EGR transducer cap missing. The component is part of the engine emission system. It is designed to lower NOx emissions, and every component which completes the EGR system, including the very important backpressure transducer, must be in it's original design with no parts missing. If you were to have your vehicle smog checked with a missing cap, the smog technician will fail your vehicle and identify it as having a defective EGR system.
As far as the role the transducer cap plays and why it's actually important to have, even though it seems to play an insignificant role... we must considering how the back pressure transducer works. The transducer valve determines how much vacuum to allow through it's mechanism based on the amount of pressure in the exhaust system. The vacuum allowed will be used to open the EGR valve, and allow exhaust flow to the intake manifold. The system is designed to reduce NOx.
The back pressure valve needs a vent in order to determine exhaust pressure accurately. The valve is very sensitive to pressure, and it's vent (outlet) needs to allow for a precise amount of flow. The transducer cap serves two purposes. It controls the amount of vent flow as well as protects the transducer filter.
posted by SmogTips Support
