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How to Replace an EGR Valve

Dan Ferrell writes about DIY car maintenance and repair. He has certifications in Automation and Control Technology and Technical Writing.

EGR valve with carbon buildup.

EGR valve with carbon buildup.

EGR Valve Replacement

An exhaust gas recirculation (EGR) valve, when it is working correctly, recirculates exhaust gases through the engine to reduce emissions of oxides of nitrogen (NOx).

Usually, EGR valves don't totally fail. But stopped-up passages and ports will greatly affect valve and engine operation.

A bad exhaust gas recirculation (EGR) valve can cause several symptoms:

  • Hard starting
  • Rough idle
  • Hesitation during acceleration
  • Engine power loss
  • Overheating
  • Stalling
  • Bad fuel economy
  • Increased harmful emissions
  • Pinging
  • Detonation
  • Knocking
  • Surging

So replacing the valve most often requires checking and removing buildup from passages and the intake manifold and sometimes from under the throttle body as well.

You want to know for sure the new or newly cleaned valve operates correctly; otherwise, driveability problems and high exhaust emissions will persist, even after installing the new valve.

How to Replace It

This guide will help you replace the most common vacuum-controlled, electrical-vacuum-controlled, and other electronic-controlled EGR valves.

In most models, replacing an exhaust gas recirculation (EGR) valve is not difficult. You can do it in your garage in about an hour or two depending on your particular system, using some common tools and a good solvent like carburetor cleaner.

If you need help, consult the vehicle repair manual for your particular car make and model. You can get an inexpensive aftermarket repair manual from one of the local auto parts stores in town or order one from Amazon, like this Haynes manual. These manuals come with step-by-step procedures and pictures for many maintenance and repair jobs you can do at home.

Before you install the new unit, make sure you have the correct EGR valve replacement for your particular car make and model. If you are replacing the valve, take the old valve with you to the auto parts store and match it with the new one. If you're ordering from a web store, match your old valve to the pictures that may be shown on the site.

To get the right part, you'll need information about your particular car make and model, and engine size. The vehicle identification number (VIN) can be useful to get the correct valve calibration for your particular model. You can find your VIN on your registration card or a small plate on the driver's side of the dashboard, better seen through the windshield from outside the vehicle.

Some new EGR valves come with their corresponding gaskets. If yours doesn't include one, buy the necessary gasket(s), or buy gasket paper so that you can make your own.


Tools and Items You'll Need

I. Locating the EGR Valve

II. Removing the EGR Valve

III. Cleaning the Valve, Passages, and Ports

IV. Installing the EGR Valve

Tools and Other Items You'll Need

  • New EGR valve
  • New EGR valve gasket
  • Phillips screwdriver
  • Standard screwdriver
  • Adjustable wrench
  • Box-end wrench set
  • Ratchet
  • Socket wrench set
  • Dull scraper or plastic scraper
  • Safety goggles, if necessary
  • Chemical resistant gloves, if necessary
  • Carburetor cleaner, if necessary
  • Scratch awl, if necessary
  • Shop rag
The EGR valve is usually located around the top or backside of the engine.

The EGR valve is usually located around the top or backside of the engine.

I. Locating the Valve

The EGR valve is usually located around the top or backside of the engine, and to one side of the cylinder head, close to the intake manifold, or on the intake itself. Depending on your particular model, the EGR valve may connect to a pipe that goes to the exhaust manifold. But you won't have much of a problem working with either type of valve.

If you're still unable to locate the valve, look it up in your service manual, which probably has a photograph or image of the valve itself. But, if you don't have the manual, visit an auto parts store on the web and look for the valve using the information from your vehicle. Many online stores will have a picture of the particular valve you're looking for.

II. Removing the EGR Valve

Different types of EGR systems are in use today. So you may need to disconnect more than one hose, electrical connector, or sensor to remove the EGR in your vehicle. If necessary, consult your vehicle repair manual.

  1. Make sure the engine is cool and disconnect the negative (black) battery terminal. Depending on your vehicle model, you may need to enter a security code to operate the radio or some other electrical device after reconnecting the battery. Consult your car owner's manual and make sure you have this information, if necessary.
  2. Then, remove the engine cover or air cleaner duct, if necessary, to gain better access to the EGR valve. Use a Phillips or standard screwdriver.
  3. Disconnect the vacuum hose from the top of the valve by hand, depending on your model. If you need to remove more than one vacuum hose, you may one to label each one to make sure you install back the hoses to their corresponding ports.
  4. Check the condition of each vacuum hose. Replace those that show signs of wear or damage.
  5. Unplug any electrical connectors from the EGR valve or sensors, as necessary.
  6. Does your valve connect to a steel pipe? Use an adjustable wrench to loosen the pipe nut.
  7. Then, loosen and remove the two or three mounting bolts holding the valve in place using a box-end wrench or ratchet and socket. You may need to apply lubricant to the bolts if they seem pretty tight. The bolts are continually exposed to heat and rust, which can make them difficult to remove.
  8. If your valve is attached to a pipe, finish disconnecting the valve from the pipe now.
  9. Remove the EGR valve and valve gasket from their mounting.
Carbon buildup inside the intake manifold can also interfere with proper EGR system operation.

Carbon buildup inside the intake manifold can also interfere with proper EGR system operation.

III. Cleaning the Valve, Passages, and Ports

The EGR system includes several components like the EGR valve, hoses, sensors, the control circuit, pipes, ports, and passages. Replacing a bad EGR valve without checking or cleaning these other components can lead to system failure. Exhaust gases are prone to clog passages with carbon deposits wherever they flow. Make a visual inspection of exhaust passages through the system to make sure the new EGR valve will work properly. On some vehicle models, you may need to remove the fuel injectors or the intake manifold to properly dislodge carbon buildup from passages. Consult your repair manual, if necessary.

  • After you have removed the valve, use a dull or plastic scraper to remove any traces of gasket material off the base of the valve (if you're reusing the same valve), and the intake or exhaust mounting surface.
  • To remove buildup, put on your goggles and chemical-resistant gloves and spray carburetor cleaner on it. If you are cleaning the valve itself, be careful not to let solvent reach the valve's diaphragm or electrical circuits or contacts.
  • Let the carbon soak in the solvent and then use the scratch awl (or screwdriver or another similar tool) to scratch off carbon deposits from around ports and passages. Be careful not to scratch the mounting surfaces, though. A stiff wire brush is an ideal tool for the job, but, often, carbon deposits can be hard as a rock to remove.
  • Some newer engine models use multiple EGR ports. Sometimes it's necessary to remove the intake manifold to properly clean all the ports to avoid driveability problems. If you need to remove the intake manifold, you may need to replace the intake gasket as well. Consult your vehicle repair manual, if necessary.
  • Check the throttle body bore and plate for carbon buildup and clean as necessary.
  • Use the pipe cleaning wire brush and a shop rag to clean inside a pipe, port or intake as necessary. For more help with maintaining your new EGR valve and the EGR system exhaust passages, check this post: How to Clean an EGR Valve.

The next video gives you some visual clues about how to clean the EGR valve.

Use a torque wrench to tighten the EGR valve bolts.

Use a torque wrench to tighten the EGR valve bolts.

IV. Installing the EGR Valve

Installing the EGR valve is a simple process. However, you need to make sure the valve is properly seated and tighten the bolts to the proper torque.

  1. Position the new valve against the pipe and thread the pipe's nut by hand, if yours comes equipped with it.
  2. Position a new gasket and start the valve's mounting bolts through the EGR and gasket by hand.
  3. Tighten the mounting bolts with the wrench — and the pipe, if equipped, with the adjustable wrench. Then, finish tightening the bolts with the torque wrench to prevent overtightening the bolts and damaging the gasket, or leaving the bolts loose and causing a leak. Check the bolts' torque specifications for your application in your vehicle repair manual.
  4. Plug in the valve electrical connector, reattach vacuum hoses, and replace the air cleaner duct and any other components you had to remove to gain access to the valve.
  5. Connect the negative (black) battery terminal.
  6. Start the engine and check that the EGR valve is working correctly and there are no vacuum leaks.

In the next video, you can watch the installation of an EGR valve.

Replacing a faulty EGR valve doesn't involve too much work, but removing carbon buildup from passages, ports, intake, and other places may take some effort. Removing buildup will help increase the valve's service life and help good engine operation. The main causes of carbon buildup are driving mostly short trips or within the city, and an increase in engine oil consumption due to wear and tear.

If possible, make a quick check of the passages under the EGR valve every other year, and clean the system as necessary or about every 60 months to prevent driveability issues. Check your vehicle service manual for the maintenance intervals of the emission control system.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: Where do the EGR and vacuum hoses go on my 1998 Nissan Pathfinder?

Answer: I believe this photo will help you locate the valve. It's the round component under the hoses:

© 2015 Dan Ferrell