Audis are known for being reliable, eco-friendly vehicles, and much of that reputation stems from their highly efficient exhaust gas recirculation valves. The exhaust gas recirculation valve, more commonly known as the EGR valve, helps remove noxious chemicals from your Audi’s exhaust system. This minimizes the effects of your Audi’s emissions on the environment, making your vehicle more sustainable. When the EGR valve fails, it can have serious consequences for both your vehicle and the environment at large.
How the EGR Valve Works
Depending on the age and model of your Audi, your vehicle may have either a vacuum-operated EGR valve or an electronically-operated EGR valve. Although these valves operate in slightly different ways, they share the same purpose: cleaning up your vehicle’s exhaust. More specifically, your vehicle’s EGR valve filters nitrous oxides from its exhaust manifold back into its intake manifold. Not only does this prevent the nitrous oxides from leaking out into the environment, but it also helps regulate the engine’s temperature. This is why a working EGR valve benefits you, your vehicle, and the world around you.
Common Causes of EGR Valve Failure
Because the EGR valve is routinely exposed to harmful chemicals and extreme temperatures, there are several reasons why it may fail. The main cause of EGR valve failure is clogs within the EGR system. Over time, the nitrous oxides that filter through the valve can leave residue within the component. Eventually, this residue may build to the point that the valve cannot work properly. Similarly, the tube leading up the valve may also grow clogged with residue, which can further interfere with the valve’s ability to operate.
In addition to clogs and blockages, another potential cause of EGR valve failure is issues with the differential pressure feedback sensor. This sensor, which detects pressure changes within the exhaust manifold, determines when the EGR valve turns on or off. Therefore, if the sensor shorts out or becomes covered in debris, both it and the EGR valve may stop working.
Finally, if your Audi relies on a vacuum-operated EGR valve, problems with the vacuum may translate into issues with the valve. More specifically, if your vehicle’s motor cannot produce enough power to run the vacuum, then the vacuum will not transmit enough pressure to the EGR valve. This will reduce the valve’s ability to filter out toxins.
Signs of a Malfunctioning EGR Valve
Fortunately, because the EGR valve directly affects your Audi’s engine, the symptoms of an EGR valve malfunction are fairly difficult to miss. For example, one of the most common signs of a failing EGR valve is a loss of engine power. Without the nitrous oxide filtered to the intake manifold by the EGR valve, your vehicle’s engine will become much less efficient and may begin to lack power at lower speeds. This may be accompanied by rough idling and rough acceleration.
Furthermore, EGR valve failure can cause your vehicle’s engine to produce loud knocking noises. Because the nitrous oxides provided by the EGR valve help regulate engine temperature, the absence of these chemicals will allow the engine to heat up. This could cause your vehicle’s fuel to combust before it should, which will likely produce knocking noises.
Last but certainly not least, two more signs of EGR valve malfunctions are increased emissions and illumination of the check engine light. As the primary purpose of the EGR valve is to reduce your vehicle’s emissions, any issues with the valve will naturally lead to an emissions increase.
Additionally, because the EGR valve is connected to both your vehicle’s engine and its CPU, EGR valve problems typically cause the check engine light to illuminate. Although other problems may cause these two symptoms to occur, the appearance of both signs at once almost always indicates that something is wrong with the EGR valve.
How We Can Help
The EGR valve is a specialized component that 
requires considerable experience to repair, and that’s where we come in. Our technicians here at Momentum Motorworks are talented individuals who are proud to provide great service to customers in Alabaster, Homewood, Helena, Hoover, Mountain Brook, Vestavia, and Birmingham, AL. Regardless of what’s ailing your German vehicle, we’ll happily help you get it back on the road in no time, so give us a call today to find out what we can do for you.