How to Clean an EGR Valve


Cleaning your EGR valve will solve your car's engine performance issues related to any clogging or system passages problem with the valve. Even more importantly, it'll prevent serious engine damage and expensive repairs.

During operation, the EGR system pulls a small amount of exhaust gases from the exhaust manifold through the EGR valve, into the intake manifold, and back into the combustion chambers. Theses gases mix with the air-fuel mixture inside the cylinders to reduce high temperatures during the combustion process. The lowered temperature inhibits the formation of poisonous oxides of nitrogen (NOx). Overtime, though, this routed gases build up a hard and thick wall of carbon, locking the EGR valve opened or closed and obstructing system passages, which prevents exhaust gases from reaching the combustion chambers and increases NOx emissions.

You may recognize some of these bad EGR valve symptoms:

  • If the valve sticks open, a continuous flow of exhaust gases enters the cylinders, disrupting the combustion process. The engine idles erratically, surges, and even stalls as it warms up or as you drive at low speeds—inside parking lots for example.
  • If the valve sticks closed or passages become clogged, cylinders temperatures will increase, leading to a knocking condition (fuel ignites before the combustion)—you'll notice a tapping noise coming from the engine. In severe cases, this develops into violent detonations that will seriously damage your engine.
  • On newer car models with electronic valves, the vehicle's computer will trigger the Check Engine light or MIL (malfunction indicator light) when EGR system problems develop.

That's why car manufacturers recommend cleaning the EGR valve and passages every 50,000 miles or fewer. But you don't need to take your car to the shop. Clean the EGR valve and passages over the weekend at home using a few common tools and a quality EGR valve cleaner.

By the end of your repair, you'll have restored engine performance and saved your engine—and your wallet—from irreversible damage.


Finding the EGR Valve

Depending on your car's make and model, your engine may be using one of three common types of EGR valves: vacuum controlled (older models), electronic-vacuum controlled valve (newer models), or the new electronic controlled digital valve.

You'll locate the valve towards the top or side of the engine. However, one or more components may obstruct your view.

  • Older vehicle models use a semi-flat, round thick metal disc about three inches in diameter. You'll see a thin vacuum hose connected on top.
  • Newer models use a similar valve with a small box (sensor) on top along with an electrical harness.
  • Still other models use a cylinder or block configuration for the valve with attached sensors and an electrical harness.

Look around the side of the cylinder head (top area of the engine) for the valve. Check near the throttle body, firewall, or intake manifold. If you don't see it, search for your EGR valve online by going to an auto parts store website and entering your car's make, model and engine size to look for the valve. Most auto parts stores will show the picture of the EGR valve that applies to a particular vehicle make and model for quick identification. Look at the picture and you'll know exactly what you're looking for.

Or, better yet, consult the repair manual for your particular vehicle make and model. You can buy an inexpensive aftermarket repair manual at most auto parts stores and online. The manual tells you not only the location but provides illustrations and photos of the valve and related components, troubleshooting procedures, and the necessary steps to remove and replace EGR system components like the EGR sensor, vacuum hoses, and pipes.

Tools You Will Need
Ratchet extension
Socket set
Adjustable wrench, if removing a pipe
New EGR valve gasket, if necessary
EGR valve or carburetor cleaner
Dull scraper
Pipe cleaning wire brush
Repair manual, optional
Acid-resistant gloves

Removing the EGR Valve

After locating the valve and moving accessories out of the way to gain access to it, it's time to remove it.

  1. Some valves have a thin vacuum hose attached to it. Carefully disconnect the hose from the valve. Check the vacuum hose for splits, softening, hardening, or cracks. If necessary, replace it. Damaged vacuum hoses cause poor EGR valve operation and EGR system failure.
  2. Follow the vacuum hose you just disconnected to the component attached at the other end, and inspect any other hoses connected to that other component as well, if any.
  3. Unplug any electrical connectors from the valve.
  4. Using a ratchet, extension, and socket, remove the valve mounting bolts. You'll need to unscrew two to four bolts, depending on your particular model. Also, your valve may connect to a pipe coming from the exhaust manifold. To remove the pipe, use an adjustable or crescent wrench or disconnect the pipe at the exhaust manifold.
  5. After removing the EGR valve, check the valve's gasket(s). If it still looks in good shape, recycle it. Otherwise, buy a new one. Some auto-parts stores only sell the gasket as part of a new EGR valve. Yet, you can buy gasket paper and make your own. Save the remaining paper for other gaskets you'll need in future repairs.

EGR Valve Cleaning

Put on your safety glasses and acid-resistant gloves, you're going to remove carbon deposits from the surface, entry and exit ports on the valve, and corresponding intake and exhaust ports and pipe.

  1. Spray carbon deposits with EGR-valve or carburetor cleaner. Immediately wipe cleaner off plastic parts and electrical components still attached to the valve to prevent damage.
  2. Use a dull scraper and a pipe cleaning brush to scrub carbon buildup. Then use a soft brush to remove the carbon and wipe the surface using a clean rag. Repeat the process as necessary. And don't gouge mounting and sealing surfaces, or you'll cause exhaust gases to leak.
  3. To deal with rock-hard buildup, leave the valve soaking in the cleaning solution for a few minutes. Just don't let the cleaner touch electronics, electrical components, or plastic parts, or you'll ruin the valve.
  4. Repeat step 3 to fight stubborn carbon deposits. Some people leave the valve soaking in the cleaning solution overnight, but fumes emanating from the strong chemicals in the cleaner gradually destroy sensitive valve parts, so do it at your own risk.
  5. If you know carbon deposits remain inside the intake manifold, apply the EGR valve cleaner through the intake manifold—read the instructions on the product's package. This will also help remove carbon from the intake valves. Seafoam is another popular product for this purpose. Or, if you prefer, take your car in for a carbon cleaning service.
  6. Once you've removed all the carbon buildup and cleaned each passage and sealing surface, reassemble all the components, including the gasket.
  7. Put everything back in place and check that the symptoms have disappeared.

EGR Valve Operation

Closed position (left), and opened position (right).
Closed position (left), and opened position (right). | Source

Carbon deposits accumulate rapidly, especially if most of your driving happens within the city—going to work, driving to school, quickly running to the grocery store, and doing similar errands. This driving pattern doesn't allow the engine to reach operating temperature and run long enough to remove harmful carbon deposits.

A cleaning EGR valve job doesn't have to wait until engine performance issues appear or the Check Engine light comes on. Clean the valve and EGR system passages every 18 or 24 months as part of your vehicle maintenance schedule. Bookmark this guide now to save time, money, and trips to the car shop.

Test Your Knowledge of Bad EGR Valves

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