How To Clean an EGR Valve Without Removing It

The EGR valves (exhaust gas recirculation) are designed to stop nitrogen oxide pollution. They have to work right or your check engine light will come on and you can fail an emissions test. Sometimes, the EGR valves can break and stick wide open. Then, it’ll suck so much air that the engine will idle poorly and run badly because there would be more air than fuel mixture in the combustion chamber.

The hot exhaust gas comes out of the engine and some of it goes into the EGR valve. When the EGR valve opens up, it sends a hot exhaust gas back into the intake manifold, so which sends already-burned gas into the engine. So, the engine temperature is lower and when it combusts, it won’t create nitrogen oxides and pollute the atmosphere.

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Over time, the carbon builds up and will clog the EGR valve. If you are a skilled mechanic, you won’t have a hard time removing and cleaning your EGR valve. But, if you are not a mechanic, here is how to clean an EGR valve without removing it:


How To Clean an EGR Valve Without Removing It

How To Clean an EGR Valve Without Removing It

Over time, the EGR valve gets dirty. The carbon builds on the walls of the EGR valve and it can cause premature wear. You should clean your EGR valve every 20,000 miles. The good thing is that you don’t have to remove your EGR valve in order to clean it. Here is how to clean an EGR valve without removing it:

1. Gather the needed cleaning supplies

Gather the needed cleaning supplies

In order to clean your EGR valve, you will need to have a clean microfiber towel, an EGR valve cleaner, and latex gloves. The EGR valve cleaner is a corrosive product, so it’s best if you wear gloves while cleaning the EGR valve. I personally use the LIQUI MOLY EGR valve cleaner (check the price on

2. Locate the EGR Valve

Locate the EGR Valve

Different vehicles will have their EGR valve in different places. The EGR valve is attached to the intake manifold. Usually, the EGR valve is located where on the backside of the engine. If you do not have direct access to the EGR valve without removing a lot of parts, you can find the nearest access to the EGR valve. On some vehicles, the closes access point to the EGR valve is through the turbo.

3. Gain access to the EGR Valve

How To Clean an EGR Valve Without Removing It

Gain access to the EGR valve by removing the cover. Be very careful not to lose any screws or clamps. Your EGR valve might not look like the one shown in the photo, but I am sure that it won’t be crystal clear.

4. Start the vehicle and rev it to 2000 RPMs

Start the vehicle and rev it to 2000 RPMs

Start your vehicle and wait for it to reach the normal operating temperature. You will need someone to sit in the car and keep the RPMs in 2000. The sound of the engine will change because as you spray the EGR valve cleaner, the air-to-fuel mixture ratio will be different.

5. Spray half of the cleaning solution (250ml)

The EGR valve solution that I use comes in a 500ml can. Ideally, I use half of the can only. Make sure to spray little by little. You don’t want to overwhelm the engine. Short 1 second sprays will do the job just fine. Wipe the EGR valve and surrounding area with a microfiber towel.

6. Reinstall the EGR valve cover

Turn off the car and wait for the engine to cool down and then reinstall the EGR valve cover and any other parts that you had to remove to get to the EGR valve itself.

7. Scan the vehicle for error codes

At this point, the check engine light should turn itself off once the computer gets the information that the EGR valve has been cleaned. You can run diagnostics to double-check and see if there will be any other error codes associated with the EGR valve. This is the OBD2 scanning tool that I use (check price on

Most Common Signs That Your EGR Valve Needs Cleaning

There are 2 most common signs that your EGR valve needs cleaning. These signs are perfect for people that don’t have scanning tools. If you do have a scanning tool, you can go ahead and run diagnostics. The scanning tool will show any EGR-related error codes if the valve needs cleaning or replacing. Here are the most common signs that your EGR valve needs cleaning:

1. Rough Idle

The function of the EGR valve is to reduce emission gases exhausted from the vehicle. The emission gas is recirculated back to the engine through the intake manifold to be re-burned in the combustion chamber. Normally, when the EGR valve is clogged, rough idle will occur. The EGR valve can get stuck open and there can be increased fuel consumption and smoke smell while driving. If this happens, you will fail an emission test. Moreover, the check engine light will illuminate and trigger EGR error codes.

2. EGR Valve Stuck Closed

Usually, this is caused by a blockage and buildup of carbons. If the EGR valve is clogged, there is also a good chance the intake manifold is full of carbon as well. Some of the symptoms of a stuck closed EGR valve are pinging noise, tapping noise, and detonation noise, and a check engine light. You can try and clean the EGR valve with a cleaning solution. If this doesn’t solve your problem, you should replace the EGR valve.

What Is The Best EGR Valve Cleaner

Liqui Moly is a German company that produces a lot of car cleaning products. One of them is the EGR valve cleaning product. I personally have used this product for cleaning my EGR valve without removing it. The canister is 500ml and you can use it to clean your EGR valve twice. The Liqui Moly EGR valve cleaning product will not damage any seals on the engine. It cleans nicely and is very easy to use. After you used half of the cleaning product, store it for your next EGR valve cleaning.

Igor Iwanowski

I am a certified Automotive Service Excellence (ASE) mechanic since 2018. I specialize in Brake systems, dashboard warning lights, EGRs, general engine problems, EVAP and Emissions issues.

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