EGR Valve also known as the Exhaust Gas Recirculation Valve or the EGR solenoid, This valve reduces the HC emissions of an engine by reducing the combustion chamber temperature. This is achieved by routing a a portion of dirty exhaust gasses into the inlet system. Later types are electronically operated whereas early systems are purely pneumatic. Failure symptoms are increased (CO), Poor low-speed drivability, and difficult hot starting. Failure is as a result of carbon from the engine, thus a worn engine will cause premature failure of the valve.