How to Fix a Dirty EGR Valve

What Does the EGR Valve Do and Where Can I Find It?

The EGR is a system that pulls a small part of the exhaust gases from the exhaust manifold and runs it through the EGR valve into the intake manifold.  Depending on your car’s age you might have one of the 3 types of EGR’s:

1) Semi-flat, round and thick metal disc (3 inch in diameter) with a thin vacuum hose connected on top . Usually found on older vehicles
2) Semi-flat, round and thick metal disc (3 inch in diameter) with a thin vacuum hose connected on top plus a small box (with the sensor in it) with an electrical harness. Found on newer vehicles
3) Cylinder or block form for the valve with a sensor and electrical harness attached. Some other models.

The EGR can be found around the side of the cylinder head, throttle body or intake manifold. To make identifying easier, you can check online at your auto parts store website or consult your repair manual. This will guarantee that you will find it easier and have it removed quickly for a closer inspection.

Back To Exhaust Gases

The role of gases that run through the EGR valve, is to mix with the air-fuel mixture inside the cylinders. This role helps reduce high temperatures during the combustion process that can form poisonous oxides of nitrogen (NOx).

During it’s lifetime, due to the gases that are routed through it, the EGR valve will start to get dirty. It will develop a hard, thick wall of carbon build up inside that will prohibit it from working as normal. This may become stuck ‘on’, either open or closed in its position, which will trigger weird behaviors.

Possible symptoms:

  • Engine idling erratically, stalls or surges in idling as the engine warms up or driving at low speeds -for example in a parking lot. (This happens when the EGR is blocked open and a continuous flow of exhaust gases enter the cylinders, disrupting the combustion process)
  • Engine knocking/tapping noise coming from the engine. This happens when the EGR is blocked closed or the passages are blocked. Cylinder temperatures will spike and lead to formation of hot spots that will ignite the fuel before the combustion should take place, causing a pinging noise.
  • Check engine or Malfunction Indicator Light (MIL) will come up on the dashboard (this applies for newer cars with electronic valves regardless of the EGR block position)

Carbon deposits appear rapidly when most of the driving happens within the city and on short distances due to the engine not reaching operating temperatures or running long enough to remove harmful carbon deposits. Read more about carbon deposits and how to eliminate them, here.

To make sure you protect your engine and bypass headaches it is recommended that you clean your EGR valve and passages once every 40,000 – maximum 50,000 miles. It’s best not to wait until performance issues appear or your Check Engine light comes on.

This operation is simple, you can do it yourself over a weekend at home with a few common tools and a good quality EGR valve cleaner. Your engine will be happy, performance will return and your wallet & engine will be saved from unnecessary damage.

How to Remove Your EGR Valve

Step 1. If your EGR valve has a thin vacuum line attached to it, carefully disconnect it from the valve.

Step 2. Check the vacuum hose for splits, hardening/softening or cracks. If needed, replace it (vacuum hoses that are damaged cause poor EGR valve operation or EGR system failure)

Step 3. Follow and inspect the vacuum hose from the disconnected area all the way to the next component and the components linked to it. It’s important to be sure that the entire vacuum system is in good condition.

Step 4. Unplug electrical connectors from the valve

Step 5. Remove the valve mounting bolts. You might need a ratchet, extension and socket to make it happen. If your valve connects to a pipe coming from the exhaust manifold, you will need to remove that as well by using an adjustable or correctly sized wrench.

Step 6. Having successfully removed the EGR valve, check the valve’s gasket. If it looks bad, buy a new one, otherwise reuse it. If you’re replacing it, you can buy a new one or buy hi-temp gasket paper and make your own, keeping the remaining paper for other gaskets you might need in the future.

6 Steps to Clean Your EGR Valve

For this part you will need to make sure you’re safe. Grab yourself a pair of safety glasses and gloves and get ready to remove carbon deposits from the surface of the valve, entry port and exit port + corresponding intake and exhaust ports and pipe. You will need a good quality EGR valve spray cleaner. (even a carburetor spray cleaner might help do the job)

Step 1.

Spray the carbon deposit with the EGR valve spray cleaner and make sure you immediately wipe off any of it from the plastic parts and electrical components attached to the valve so they don’t get damaged. Let it soak.

Step 2.

Using a dull scraper and a pipe cleaning brush, scrub the carbon buildup. Finish off by using a soft brush and a clean rag to remove the carbon and wipe the surface clean. Do this until the build-ups are gone. !! Pay attention not to gouge mounting and sealing surfaces or you will cause exhaust gases to leak.

Step 3.

In the eventuality of rock-hard carbon buildup, soak the valve in the cleaning solution and let it sit for 10 minutes. Just make sure that the cleaner doesn’t touch electronics, electrical/plastic components or your valve will be compromised. If this fails, don’t panic. Some people find that to remove stubborn deposits you might need to leave the valve soaking in the cleaning solution overnight. !!Please note that the fumes emanating from the strong cleaning chemicals in the cleaner can destroy valve parts. Leave it soaking overnight at your own risk.

Step 4.

Check the intake manifold. If there are carbon deposits inside it, apply the EGR valve cleaning spray through the intake manifold. To be sure, check the product’s instructions before you do this step.

Step 5.

Once all carbon buildup has been eliminated and surfaces have been cleaned. Make sure to clean each passage and sealing surface as well. Then reassemble all components.

Step 6.

Put everything back together, double check that you did not forget any vacuum hose or electrical plug and give it a key start to see if symptoms have disappeared.

This concludes the operations needed on how to fix a dirty EGR valve. It’s not a very hard task to do, however since it requires some attention and possibly more work on stubborn carbon deposits, we recommend that you do it over a weekend so there is no rush.

If you’re not keen on taking up such a task, you can find a carbon cleaning service at most repair shops and garages. But it would be a shame to not get to know your car better. 😉

Bonus tip: One way to extend the mileage between servicing and to enjoy more benefits would be to use a fuel additive that removes carbon deposits while you drive. Such as CleanBoost® Maxx™, a fuel additive that doubles as a combustion catalyst to improve performance.  CleanBoost® Maxx™ is  a cost effective way to treat fuel. Just 1 oz. treats up to 30 gallons & it will maximize both performance and fuel economy while reducing emissions as third party testing proves. Because the fuel will burn cleaner, it will result in less carbon deposits on internal components including the EGR valve.

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Tech Guy

Automotive enthusiast, passionate about Jeeps, hot-rods, turbos, performance, efficiency, diesels, fuels, high performance oils, additives and anything with an engine.

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