The EGR valve is an essential part of your Audi. It is responsible for processing your engine’s exhaust gases. When the air and fuel is ignited at high temperatures inside your engine, gases are created which are harmful both to people and the environment. The EGR valve reintroduces these gases to the engine, where they can be fully burned up before being sent along the exhaust system to exit your vehicle. In this article, we will look closer at the valve and how you can tell when it’s time for repairs or replacement.
Different Types of EGR System
Vehicles of different ages as well as those that run on gas or diesel can use a variety of types of EGR system. Let’s take a closer look at these.
- Older Vehicles will usually have an EGR valve which is a thick, round metal disc that sits on the side of the engine. This type of valve is operated by a vacuum hose.
- More Recent Vehicles use electronic-vacuum EGR valves which are contained inside a small block or cylinder. It works in the same way as earlier versions but is more precise.
- Modern Vehicles use similar electronic EGR systems with the addition of a variety of components that vary between make and model. Some use a digital valve to replace the vacuum-controlled valve of older models.
- Some High Performance Vehicles have used experimental EGR designs which use EGR jets at the base of the intake manifold.
- Some High Efficiency Engines such as those that implement variable valve timing, forgo the EGR valve altogether.
Signs of EGR Valve Failure
Common symptoms of EGR valve failure experienced by Audi drivers include:
- rough idling
- frequent stalling
- a fuel smell
- poor gas mileage
- noises such as knocking, pinging or tapping
- failed smog/emissions test
- illumination of the check engine light
Two Types of Failure
As the EGR is a valve, there are two types of failure: one where the valve is stuck open and the other, where the valve is stuck in the closed position. These failures will bring with them their own unique symptoms.
An EGR valve which remains open results in a constant flow of exhaust gases into the intake manifold. This will result in any one or more of the symptoms listed below:
- Rough idling, in particular when the engine is cold or running at low engine speeds.
- Stalling at idle.
- Fuel odors can be slight or strong. This happens because of increased hydrocarbons leaving the tailpipe.
- Emissions test failure due to the increase in hydrocarbons in the exhaust emissions.
- Illumination of the check engine light. This is also known as the engine management light (EML), and it will be triggered by your Audi’s onboard computer, illuminating on the dashboard.
When the EGR valve is stuck closed, the flow of exhaust gases will be blocked from entering the intake manifold. One of the following symptoms will be noticed:
- Noises when at low RPM, such as a pinging noise or a tapping noise. This is the sound of the fuel meeting high temperatures in the engine.
- Loud detonations is caused by a second ignition occurring quickly after normal ignition which can cause engine damage.
- Emissions test failure: High temperatures created inside the engine by the failure of the valve will cause large amounts of nitrogen oxide to form and be released through the tailpipe.
- Illumination of the check engine light: As with scenarios where the valve is stuck open, the onboard computer (ECU) will trigger the EML when it detects poor engine function.
A Helping Hand from Bavarian Auto
At Bavarian Auto, we want to offer you the helping hand you need when faced with parts failure in your Audi. EGR valve failure can be a stressful thing to deal with, and we want to be your trusted service center you can count on to help you quickly diagnose and repair this issue. We proudly serve the residents of Ootelwah, Hixson, and Chattanooga, TN and surrounding communities. Come to a fast and stress-free resolution to your Audi’s problems, be this with the EGR valve or with any other system in your Audi. Call us today for diagnostics, inspections, maintenance and servicing.