Theory of Operation

WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

When the Exhaust Gas Recirculation (EGR) Valve is opening to a position and uses too much current to achieve that position, the diagnostic will fail. Also at every key on, the EGR valve tries to recalibrate it's position. The valve shaft will move until it comes into contact with the valve. If the distance the valve shaft must move is different by a calibrated amount than the original learned movement the diagnostic fails. The valve will perform this auto zero function at every key on and every time the valve is commanded closed throughout the engine operating cycle. The Powertrain Control Module (PCM) will illuminate the MIL lamp after the diagnostic runs and fails in two consecutive drive cycles. The PCM will also turn on the ETC lamp. During this time the PCM will no longer control the EGR valve. The MIL lamp will turn off once the diagnostic runs and passes in four consecutive drive cycles.