What is an EGR Valve and When It Should Be Repaired?

EGR valve.
This is a typical EGR valve. It's easy to clean or replace your EGR valve if your car or truck's performance starts to suffer. photo CC Licensed by Nevada Tumbleweed

The Basics

The Exhaust Gas Recirculation (EGR) valve helps your car more efficiently and completely burn the car's fuel by recirculating a portion of your exhaust and running it through the combustion process again. This results in a cooler, more complete burn of the fuel which decreases your car's noxious emissions by prohibiting the formation of some harmful gasses. That sounds very complicated, I know, and scientifically I guess it is pretty complex.

But the part that you need to know about and understand is much easier to wrap your head around. If your EGR valve is faulty or clogged, your engine starts to run badly. You also begin to pollute the atmosphere with exhaust gasses that your car is normally not dumping into the air. Regardless of your motivation -- economical or ecological -- a faulty Exhaust Gas Recirculation valve should be cleaned or replaced as soon as possible. If you're still interested in learning about your EGR valve, you'll find some helpful info below, along with a little troubleshooting help if you think your valve is bad or on its way out. 

Pros

  • The EGR valve is vital to your car's emission controls. Exhaust gas recirculation helps to keep huge amounts of unburned fuel from being released into the atmosphere. This unburned fuel is thought to be a huge contributor to greenhouse gas build-up. That's why an EGR system became mandatory on all new vehicles some time ago. 

    Cons

    • When the EGR valve goes bad, it must be replaced. Unlike some emissions control devices that can go bad without affecting the drivability of the car or truck, a bad EGR valve can really affect the engine's performance or even cause it to stop running altogether. The good news is you can clean it.

      Description

      • EGR Valve = Exhaust Gas Recirculation Valve.
      • The EGR valve controls formation of noxious emissions.
      • Rough idle and poor acceleration can be caused by a faulty EGR valve.

      Guide Review - EGR Valve

      The EGR valve, or Exhaust Gas Recirculation valve, is a vacuum controlled valve which allows a specific amount of your exhaust back into the intake manifold. This exhaust mixes with the intake air and actually cools the combustion process. Cooler is always better inside your engine. The exhaust your EGR valve recirculates also prevents the formation of Nitrogen related gasses. These are referred to as NOX emissions and are a common cause for failing emissions testing. Unfortunately, your EGR valve can get stuck, causing NOX gasses to build up. You'll know if your EGR valve is stuck or malfunctioning because your car will experience symptoms like rough idle and bucking on acceleration. Fuel mileage will also suffer, and you may see a Check Engine light followed by a readable code in your car's OBD-II or newer computer. 

      If you're considering the choice of whether to clean your EGR valve or simply replace it to get your emissions control system back up and running (and pass your state's vehicle inspection or emissions testing!), you need to do a little cost analysis.

      For the purposes of this website, we assume your time is mostly worthless, that's why you're doing your own repairs. But if an EGR valve for your car is only $35, it's well worth installing the new part if you can afford to.