EGR (Exhaust Gas Recirculation) valves are designed to open and close at specific points during the engine cycle to allow carbon dioxide into the combustion chamber, thereby cooling the chamber and its contents to reduce the amount of gaseous NOx (nitrogen oxide) emissions. There are a few symptoms that indicate EGR valve stickiness, and they should be resolved as soon as possible to avoid engine damage.
EGR Valve Stuck in the Closed Position
An EGR valve that is stuck in the closed position will raise the temperatures in the combustion chamber, creating a knocking or pinging. This is especially noticeable in situations where the vehicle is accelerating or cruising. EGR valves stuck in the closed position are especially dangerous for vehicles equipped with turbos since the high temperature and constant exposure will eventually cause the turbo to seize.
EGR Valve Stuck in the Open Position
If the EGR valve is stuck in the open position, the vehicle will experience a rough idle or frequently stall. If the valve is not completely stuck open but never achieves a tight seal when it closes, the engine can "miss" or shudder because of the improper mixture of the combustion elements.
EGR Valve Opens Too Much or Too Soon
Sticky EGR valves that open too much or too soon will cause the vehicle to stumble or hesitate when accelerating. Experiencing a loss of power, when accelerating, may also be a symptom of a sticky EGR valve.