VW EGR Vacuum Solenoid - Pierburg 078906283C

The EGR valve controls the flow of exhaust gases to the intake manifold and is responsible for helping control fuel consumption and reduce emissions under certain operating conditions. The EGR valve is closed unless otherwise commanded open. EGR valves will experience wear and tear over time due to the environment in which they operate. The main cause of failure is carbon buildup from the exhaust gases along the EGR and intake system passages. Over time this will clog tubes, exhaust gas channels, and eventually the EGR valve itself. This will restrict flow but more commonly it will cause the EGR valve to stick in an open or closed position.

A failed EGR valve will cause a check engine light and engine performance issues. An open valve will affect the air-fuel ratio which will result in reduced power and fuel efficiency. A valve that is stuck closed will cause high combustion chamber temperatures resulting in increased emissions. High combustion chamber temperatures due to a stuck closed EGR valve can also cause engine knock (pre-ignition) which can severely damage an engine.

In addition to the mechanical issues that the EGR system faces, it can also suffer from electrical challenges such as from the EGR Control Solenoid which is an output from the vehicle ECU that is used to control the EGR Valve based on various inputs received. If the EGR Valve Solenoid fails, it causes the system to become inoperative and thus will trigger a check engine light along with various drivability issues.