Nitrogen is all around us. In fact, almost 80 percent of our air contains nitrogen. Nitrogen becomes a problem after it is exposed to the extreme temperature in the combustion chamber of our engines. It is at this point that the gas that is normally inert becomes reactive, which causes it to release harmful nitrogen oxide or NOx from the exhaust system into the atmosphere. That’s where the EGR valve plays an integral role.
In this article, we will explore what exactly an EGR valve is, what it does, and how to know if yours is going bad.
What is the EGR valve?
The EGR (exhaust gas recirculation) valve is integral to your vehicle’s engine management system. As the name implies, the EGR valve recirculates a predetermined amount of exhaust gas to the engine’s intake system which results in reduced fuel consumption, increased engine efficiency, and lower Noxemissions.
In newer vehicle models, the traditional EGR valve system has been replaced with a newer device that is designed to cool the emissions before they pass from your engine back into your emission system. This newer system is cooled by both engine coolant and ambient air.
How does the EGR work?
The EGR helps minimize the amount of NOx that is released into the air by sending a precise amount of exhaust gas to be sent back through the intake system. This process effectively changes the entire chemical makeup of the air that enters the engine.
The diluted mixture contains less oxygen and therefore burns much slower, which decreases the temperature in the combustion chamber, reducing NOx production and providing a much cleaner and more efficient exhaust.
The EGR valve opens and closes as is necessary. The valve will be closed as the engine is starting up. While the engine is idling or operating at a lower speed where only a small amount of power is needed, the valve will gradually open. The EGR valve may be open by up to 90 percent while the engine is idling.
Three Reasons an EGR Valve Might Go Bad
- Faulty Temperature Sensor: As noted, the primary function of the EGR valve is to reduce the nitrogen oxide levels that are released into the air. However, the EGR valve also plays a key role in increasing fuel efficiency due to the way it regulates the pressure and temperatures inside of the engine cylinders.
When operating correctly, the EGR valve only opens or closes at very particular times. The EGR temperature sensor is the device that sends the information that the valve needs in order to know when to open. The moment the engine cools to a certain temperature, the valve automatically closes again.
One of the most common sources of an EGR failure is actually a temperature sensor failure. A faulty EGR temperature sensor that is sending faulty readings to the EGR valve could be the result of carbon build-up.
- Clogged EGR Pipe: The EGR system sends the exhaust back through the engine via a piece of tubing, called the EGR pipe. The exhaust itself carries a large number of contaminating After a while, these substances can build up on the inside of the pipe. If enough time passes, the deposits from these substances can clog the pipe.
If an EGR pipe is clogged your engine can run into the same types of problems that a bad EGR sensor can cause. The temperature of the engine can rise to dangerously high levels.
Fortunately, if your EGR pipe is clogged, a mechanic can fix the issue pretty easily. The EGR pipe just needs to be removed and then sprayed and scrubbed with a carburetor cleaner. This cleaning solution is formulated to loosen up any deposited buildups before the mechanic scrubs it free with a specially designed brush with metal bristles.
- Sticky EGR Valve: A clogged pipe is not the only part those contaminants can wreak havoc on. They can also build up on the EGR valve itself. As time passes, those substances can make it more difficult for the valve to function. The grime can actually cause the valve to become stuck open or closed. Neither of these scenarios are ideal for the EGR system.
Heynneman European for Your Audi’s Needs
If you suspect that your EGR valve is going bad, 
you should bring your car to our reputable and licensed mechanics right away. If you live in the Larkspur, Kentfield, Corte, Mill Valley, San Anselmo, Fairfax, or San Rafael, CA area, for the best service, contact Heynneman European! Call us today to set up your convenient appointment.
