Your EGR valve recirculates exhaust gasses into the intake for more complete and thorough burning. Recycling these gasses reduces nitrous oxide, or NOX, emissions. When your EGR valve is not working, the valve will stick and prevent the exhaust from recirculating. This will also negatively affect your idle and can cause hesitation when accelerating. Purchase a replacement EGR valve from most auto parts stores; however, before replacing it, troubleshoot the problem to make sure that the valve is bad.
Start the engine and wait 15 minutes or so until the engine warms up and the needle on the water temperature gauge sits in the middle of the gauge.
Open the bonnet and have an assistant rev the engine while you watch the plunger on the EGR valve. The valve will always be located on the intake manifold of your vehicle. If the valve doesn't move, there is a good chance that the valve needs to be replaced.
Pull the vacuum hose off the end of the EGR valve. Be careful not to touch the valve itself because it will be hot.
Connect the vacuum pressure gauge to the EGR valve and check the vacuum pressure while your assistant revs the engine from 1500 RPM to 2500 RPM. The vacuum pressure should hold steady somewhere between 15 and 22 PSI for many engines; however, the most important thing is that the pressure stays constant. If you notice the pressure drop off, or fluctuate wildly, the EGR valve may not be opening or closing properly.
Shut off the engine and allow it to cool down. Then unplug the electrical connector, if your vehicle is electronically controlled; otherwise, unbolt the mounting bolts that hold the valve to the intake manifold. Some EGR valves use a tube fitting that will require a special tube nut wrench to remove.
Inspect the valve openings on your EGR valve. If they are clogged with carbon deposits, you need to clean the valve or replace it.