EGR Control Solenoid: Description and Operation

On cold engine start-up the ECM receives input from the MAT sensor (Manifold Air Temperature), and if the MAT reading is less than 12~C (57~F) the EGR solenoid is off until the coolant warms to 80~C (176~F). If there is a malfunction of the MAT sensor then the ECM receives input from the coolant sensor.