What does a EGR Valve do?
The valve controlling your EGR (exhaust gas recirculation) is an important part of your car's engine. It controls the amount of nitrogen oxide emitted into the atmosphere by petrol and diesel engines by recycling part of the exhaust gas back into the engine cylinders.
How common is an EGR valve replacement?
With exhaust gases flowing through the component, it will eventually succumb to the deposits of carbon and hydrocarbons and it will ultimately seize. Replacing an EGR valve is an all too common repair.
How does an EGR valve work and what are the components?
The EGR valve is connected to the exhaust system by a metal tube. When the engine is running, the valve will be opened by the engine management system to allow the exhaust gases to travel up the tube from the exhaust system and back through into the inlet manifold, and afterwards back into the engine.
The control of this valve is either driven directly by a solenoid on the EGR unit itself or via a hose to a solenoid on the vacuum circuit that is also opened by the engine management system.
Some EGR units have a cooler as part of them, that is plumbed into the engine’s cooling system, literally to cool the exhaust gasses before they go back through.
By the exhaust gasses going back into the engine, it reduces NOx (Nitrogen Oxide) content. This is because the exhaust gas reduces the actual oxygen proportion and increases the vapour content, which in return reduces the combustion temperature peak. As more NOx is produced as the temperature rises, this method actively reduces the amount created.
What are the symptoms of a malfunctioning EGR Valve motor?
A rough idle when starting your vehicle or during brief stops (i.e. low engine speeds with a warmed-up engine) can be caused when the EGR is constantly open and a continuous flow of exhaust gases goes into the intake manifold. Poor performance can be caused when the valve is open or closed. The incorrect function of the EGR valve can cause the erratic performance of your vehicle.