9 Symptoms of a Bad EGR Valve (How to Clean It)

Exhaust Gas Recirculation (EGR) is a technique employed to regulate NOx emissions generated from air-fuel mixture combustion. The EGR valve is one of the critical components of the EGR system. This valve is responsible for redirecting a controlled amount of the engine’s exhaust gases back into the cylinder, thus helping to minimize emissions. When the EGR valve goes bad, it produces various signs. This article describes the bad EGR valve symptoms, its causes, and how to clean it. 

What is an EGR Valve?

The EGR valve is a component of the engine designed to regulate exhaust emissions (i.e., NOx) into the atmosphere. It permits a precise amount of exhaust gases to be reintroduced into the intake manifold.

EGR Valve

During the combustion process, the engine draws in air from the environment and combines it with fuel. When the air-fuel mixture ignites in the engine cylinder, its temperature rises, producing NOx (nitrogen oxides).

Without an EGR valve, these NOx emissions would be released into the environment, potentially causing severe health issues, including cancer and respiratory problems.

The EGR valve’s primary function is to manage the recirculation of exhaust gases based on the engine’s load, which helps control NOx emissions. This valve is typically closed and is operated by an integrated stepper or vacuum motor.

It makes a connection between the exhaust manifold and the intake manifold, ensuring a controlled flow of exhaust gases for optimal engine performance and reduced emissions.

Symptoms Of a Bad EGR Valve

A bad EGR valve produces one or more of the below-given symptoms:

  • Illuminated Check Engine Light
  • Increased Emissions
  • Poor Fuel Mileage
  • Loss in Performance
  • Failed Emissions Test
  • Engine Knock
  • Rough Idle
  • Fuel Smell
  • Engine stalls while idling

1) Illuminated Check Engine Light

The illuminated check engine light is one of the first signs of a faulty EGR valve. Therefore, it’s essential to keep an eye on the check engine light while driving, as it provides information about the condition of your engine components, including the EGR sensor, PCV valve, engine temperature, and MAP sensor.

If the EGR valve malfunctions, your vehicle’s computer turns on the check engine light.

Check engine light

However, the check engine light may be illuminated due to many other reasons. Therefore, you should properly check all the engine parts while check engine light is illuminating.

2) Increased Emissions

Increased Emission Level, symptoms of bad EGR valve

The main function of your EGR valve is to minimize emissions. But if this valve is not operating properly, you can expect an increase in overall emissions. In some cases, you may observe slightly more smoke from the exhaust pipe when the EGR valve becomes faulty, but this is relatively rare.

3) Poor Fuel Mileage

The EGR valve of your vehicle is responsible for recirculating an appropriate amount of exhaust gases to the engine cylinder, which helps to enhance engine efficiency and lower the temperature of the combustion chamber or engine cylinder.

Bad Fuel Economy

However, if this valve becomes stuck open, the engine may start to introduce air that has already been calculated by the MAF sensor, resulting in a lean air-fuel mixture and decreased fuel consumption. But this may seem like a positive sign, but it may ultimately cause bad damage to the engine.

4) Loss in Performance

A loss in engine performance is one of the clear signs of a faulty EGR valve.

Loss in Performance, signs of bad EGR valve

When your EGR valve becomes stuck in a closed or open position, you may experience a decrease in performance, such as during driving. This issue primarily occurs due to the combustion of a poor air-fuel mixture in the combustion chamber.

If your valve is stuck open, it permits too much exhaust gases to enter the engine cylinder, but if it’s stuck closed, it doesn’t allow exhaust gases to enter the engine cylinder, and the emissions rate will be increased.

5) Failed Emissions Test

Failed Emission Test

If emissions testing is required every six months, there is a higher likelihood that your EGR valve might be damaged. Although the emission test cannot provide a precise assessment of your EGR valve’s conditions. When your vehicle doesn’t pass the emission test, you should immediately contact the mechanic to find the root cause of the issue.  

6) Engine Knock

An EGR valve also plays a vital role in decreasing engine knocking. By ensuring a minimum temperature in the combustion chamber, this valve stops the fuel from igniting prematurely. Although this issue may not always arise with a bad EGR valve, the likelihood increases intensely when it is stuck in the closed position.

Engine Knock, symptoms of bad EGR valve

If your check engine light is on due to a malfunctioning EGR valve, listen for any knocking sounds. If you detect knocking, it’s crucial to address the issue promptly to prevent further damage to your engine.

7) Rough Idle

Rough Idle

If the valve is stuck open, it may permit either too much or too little exhaust gases into the engine cylinder, as there will be no control over the recirculation. This leads to a wrong air-fuel mixture inside the engine (which ideally should be balanced) and can result in rough idling, often accompanied by a rattling noise.

8) Fuel Smell

Fuel smell due to a faulty EGR valve

NOx emissions from your car’s exhaust pipe are dangerous and have a strong odor. Additionally, if the EGR valve is not functioning properly, your engine may start to consume more fuel than normal, releasing a large number of hydrocarbons. These hydrocarbons are mixed with the increased NOx emissions, creating a hazardous mixture of injurious gases.

9) Engine Stalls while idling

Engine Stalling

When your EGR valve is stuck open, it can cause not only rough idling but also engine stalling during idling. Although this may not appear as risky as a vehicle stalling while in motion, but it is a clear indication of a clogged or malfunctioning EGR valve. This issue warrants your attention so that you can fix it.

Read More: Bad PCV Valve Symptoms and Causes

Causes of a bad EGR Valve

Your EGR valve may go bad due to one or more of the below-given causes:

  • Carbon buildup
  • Bad EGR solenoid
  • Wiring or electrical issues
  • Mechanical failure
  • Vacuum leaks

1) Carbon Buildup

Carbon deposits may buildup in the passages of the EGR valve with time. The accumulation of this carbon causes the valve to stick closed or open. This may cause poor exhaust emissions, poor engine performance, and many other problems.

Leaking or damaged diaphragm: The EGR valve often has a diaphragm that controls its operation. If the diaphragm is leaking or damaged, the valve may not function properly, causing poor engine performance and increased emissions.

2) Bad EGR Solenoid

The EGR valve contains a solenoid that is used to control the vacuum flow to the valve. When this solenoid goes bad, it may stop the valve from closing or opening.

3) Wiring or Electrical Issues

Corroded electrical connections or damaged wires may disturb the communication between the powertrain control module (PCM) and the EGR valve, which may lead to a faulty EGR system.

4) Mechanical Failure

The inner parts (i.e., bearings, pintles, or springs) of your EGR valve may wear out with time, causing the valve to go bad.

5) Vacuum Leaks

A leak in the vacuum system may create problems in the EGR valve and stop it from working efficiently.

How To Prevent EGR Valve Failure

  • Regular Maintenance: To ensure the efficient working of the EGR valve, you need to ensure its regular maintenance. Ensure the proper maintenance of your car according to the owner’s manual.
  • Monitor Engine Performance: You should constantly monitor the performance of your engine. When you monitor a reduction in engine performance or poor fuel economy, inspect your car promptly.
  • Clean the EGR Valve: The valve of your vehicle may become blocked due to carbon deposits over time. These carbon deposits may prevent your valve from working efficiently. Therefore, it is recommended to periodically clean the EGR valves to prevent clogs.
  • Install a Catch Can: Modern vehicles contain a catch can installed to catch and condense the oil vapors produced during the engine operation before they reach the EGR valve and intake manifold. It helps to lower the amount of carbon accumulation in these parts.
  • Add Quality Fuel: The fuel quality highly affects the performance of the EGR valve. The quality of the fuel you use may affect the accumulation of carbon in the car’s engine and EGR valve. Always utilize good quality fuel to enhance your engine performance.
  • Proper Driving Habits: You should drive carefully in a harsh atmosphere, which may reduce the likelihood of the EGR valve failure.

EGR Valve Function

The main function of the EGR valve is to recirculate a specific amount of exhaust gas back into the combustor. The term “EGR” stands for Exhaust Gas Recirculation valve, which accurately describes its function.

EGR Valve Function

Recirculating exhaust gases provides several benefits to improve the overall performance of the engine. Firstly, these gases help to optimize the air-fuel ratio without the need to draw in additional air from the intake manifold.

Furthermore, the chemical composition of exhaust gases differs from fresh air. This difference allows the combustor temperature to remain up to 150 degrees Celsius cooler, resulting in cleaner emissions and enhanced overall engine efficiency.

The EGR valve operates based on the input data from different sensors, which determine when to open and close the valve according to the requirements. However, if these sensors go bad or the EGR valve becomes stuck, you may encounter issues with your vehicle’s performance.

EGR Valve Location

The EGR valve of the vehicle is usually situated at the engine top. It is usually connected to a pipe that extends from the exhaust.

However, it is important to note that this valve can be deeply embedded within the engine bay in some vehicles, making it more challenging to locate.

EGR Valve Location

To easily find the valve, locate the metal tube leading to the top of your engine, and identify the valve connected to it. However, some vehicles have the EGR valve fully integrated into the cylinder head without any external pipe.

How to Clean an EGR Valve

If your EGR valve is clogged and you want to clean it, follow the below-given steps:

  • First, park the car on a flat and level surface, ensuring that it is in the “park” mode. Engage all brakes.
  • Shut down the engine and let it cool.
  • Remove the negative cable of the battery.
  • Determine whether you have a mechanically or electrically operated EGR valve. This information can typically be found in the valve’s manufacturer manual.
  • Use a screwdriver to remove the bolts from the valve and any other components obstructing the valve.
  • When removing the valve, make sure it comes out with a gasket. If you notice any issues with the gasket, replace it with a new gasket.
  • Disconnect all electrical connections and wires linked to the valve.
  • Properly inspect the internal of your valve. If it is clogged, clean it properly.
  • To clean the valve, first wear the necessary PPEs, such as safety gloves and glasses.
  • Once you have your PPE on, begin the cleaning process.
  • Properly spray the EGR valve cleaner inside your valve until the accumulated carbon deposits are fully removed, and only the cleaning fluid remains.
  • Remove the accumulated carbon by using a blunt scraper and a pipe cleaning brush.
  • Repeat the above steps until all carbon deposits are completely removed.
  • Wipe the valve surface with a clean cloth.
  • If your valve is not cleaning with a pipe cleaning brush, then immerse your valve in the cleaning solution for a few minutes before brushing again.
  • After cleaning the valve, reinstall it back in its place by using a new gasket. Tighten the screws.
  • Reconnect the vacuum lines and electrical components.
  • Connect the negative cable of the battery again and start the engine. Perform a test drive to check the functionality of the valve.

EGR Valve Replacement Cost

The replacement cost of the EGR valve depends on the vehicle make and model and the labor cost. The average replacement cost of an EGR valve is between $210 and $820. You can expect the EGR valve itself cost between $130 and $420, while labor costs between $80 to $400.

FAQ Section

What does an EGR valve do?

The EGR valve connects the intake manifold to the exhaust manifold and controls the exhaust emissions. The main function of the EGR valve is to recirculate a specific amount of exhaust gas back into the combustor.

What are the signs of a bad EGR valve?

  • Illuminated Check Engine Light
  • Increased Emissions
  • Poor Fuel Mileage
  • Loss in Performance
  • Failed Emissions Test
  • Engine Knock
  • Rough Idle
  • Fuel Smell
  • Engine stalls while idling

Can I drive with a bad EGR valve?

Yes, you can drive, but it is not recommended to drive with a bad EGR. However, it may not instantly cause a failure, but it may cause poor fuel efficiency, increased emissions, poor engine performance, or potential long-term damage to the engine. It is recommended to fix the issue instantly to prevent further damage.

Does removing EGR increase engine power?

Yes, the EGR valve deletion may result in a slight increase in power for some engines. When an EGR delete works properly, it increases the O2 density in the engine. That means a boost in horsepower. 

How to prevent EGR valve failure?

  • Regular maintenance of your vehicle and valve
  • Fix the engine problems (such as poor combustion or misfires) immediately
  • Use high-quality fuel that can prevent carbon accumulation inside the valve
  • Regularly inspect the EGR valve for signs of damage, corrosion, or wear
  • Periodically clean the EGR valve
  • Avoid aggressive driving

How to tell if an EGR Valve is bad?

  1. A high reading of the engine warning light
  2. Failed emissions test
  3. High Emission rate
  4. Poor acceleration
  5. Engine overheating
  6. The smell of unburnt fuel
  7. A reduction in the engine performance
  8. Engine stalls while idling
  9. Unbalanced air-fuel ratio
  10. Poor fuel mileage
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