Q: how to tell if the egr is bad off he vehicle

Hi there. Checking the EGR (exhaust gas recirculation) valve off the vehicle, using a piece of vacuum hose attached to the small vacuum nipple, apply vacuum to the diaphragm (suck on the hose) which should move the valve to the open position and it should stay open until vacuum is released. In the open position, the exhaust to intake passage should allow air to freely flow. In the closed position, the exhaust to intake passage should allow no air to flow. I recommend having your vehicle’s EGR valve be diagnosed and repaired by a certified technician, such as one from YourMechanic.