The reason why today's engines have become so fuel efficient and powerful at the same time is because technology has enabled engineers to incorporate systems that manage combustion temperatures and optimizing the air/fuel mixture. One of these is the exhaust gas recirculation (EGR) system, and if it is compromised, your engine will perform noticeably poorer than normal. You would experience unusual difficulty starting the engine accompanied by a rough idle if the EGR valve is open. Other possible side effects would include pre-detonation (knock) and lack of power. On the other hand, if the EGR valve is stick in the closed position you will definitely notice the smell of a richer than normal air/fuel mix and your gas mileage will drop. This is bad for your emissions, and could result in a fail at your next inspection. The most obvious sign that the EGR valve needs to be replaced would be a check engine light. If this happens, take your car to a mechanic that can interface with your OBD-II plug and get a code from the computer.
Since the energy crisis of the 1970's, auto makers have been diligently scouring the processes of engine combustion looking for wasted energy that could potentially be put to better use or recycled. Exhaust gas recirculation uses a valve that responds to the back pressure and temperature of your engine's exhaust gas and channels it to other parts of the engine (http://auto.howstuffworks.com/fuel-efficiency/hybrid-technology/exhaust-heat-recovery-recirculation2.htm). The EGR valve offers the intake manifold access to unburnt or otherwise wasted exhaust gases that can be used to heat the air/fuel mixture. This adds to fuel economy and also aids in boosting horsepower. Your EGR valve is sometimes activated by an electronic solenoid that responds to cues given to it by the engine control computer when the exhaust gases can be diverted to other parts of the engine. The added benefit of this is also a reduction in the heaviest and richest of particulate emissions. Most vehicles have an EGR valve and solenoid governing the system, but if they do not then they will usually have multiple catalytic converters to mitigate airborne pollutants.
Replacing a broken EGR valve is all about access. It is often times harder to get to it than it is to remove it and install a new one. After locating the EGR valve, you will need to be able to successfully remove all engine components that are going to get in your way. In rare instances, you may have to cherry pick the engine. But once you have located it and have the opportunity to remove it, it is a relatively simple procedure. Obviously, this should be done with the engine off and battery disconnected. You first must remove the intake and vacuum hoses from the valve, and then disconnect the wire harness connector. After that, you can unscrew the EGR valve from its mounting location. Then replace it performing all these steps in reverse.
A car's EGR valve and solenoid can be a complicated part, and whenever possible should be replaced with the highest quality available. At Car Parts Discount, that's what we have. We offer the best aftermarket brands and original equipment manufacturers for EGR valves and other components. We know that your vehicle's emissions and performance matter, so trust that when you buy from us you are getting the part you need at the best price around.