Maintenance Tips, Tricks And Hacks For Your Vehicle

What Causes EGR Valve Failure? (Answered!)




Your car’s EGR valve is an important part of the emissions control system. It helps to reduce NOx emissions by recirculating exhaust gases back into the engine. EGR valve failure is a common issue that can occur in any vehicle, but what causes it?

In this comprehensive guide, we will discuss the causes of EGR valve failure and how to prevent it from happening.

We will also cover the symptoms of a failed EGR valve and what to do if it fails. So, if you are concerned about the health of your EGR valve or want to learn more about how to keep it functioning properly, keep reading!

Key Takeaway

  • EGR valve failure is predominantly caused by the accumulation of carbon deposits, soot particles, and dirt from exhaust gases and fuel.
  • А malfunctioning EGR valve can lead to engine damage as it can disrupt the vehicle’s air-fuel ratio, and cause overheating.

What Causes EGR Valve Failure?

EGR valve failure is predominantly caused by the accumulation of carbon deposits from the exhaust gas, leading to the valve becoming stuck open or closed and contributing to issues such as excessive carbon at the turbine end of the turbocharger and potential clogging of the VNT mechanism.

Hostile Environment

EGR valves function in a hostile environment and over time, they will inevitably experience wear and tear. This environment accelerates the deterioration of the valves, making them more susceptible to failure.

Carbon Buildup

The primary cause of EGR valve failure is the buildup of carbon deposits from the exhaust gas. These deposits can cause the valve to get stuck in either an open or closed position, severely disrupting its functionality.

Excessive Carbon at the Turbocharger

A faulty EGR can result in excessive carbon or soot at the turbine end of the turbocharger. This could lead to the VNT (Variable Nozzle Turbine) mechanism becoming clogged and sticking, which can significantly impair the performance of the vehicle.

Vehicle Inspection Failures

Vehicle inspection failures are rapidly increasing due to one common cause of EGR valve failure. The EGR valve can become contaminated, leading to it not functioning correctly and causing the vehicle to fail its inspection.

Bad Fuel

Low-quality or contaminated fuel can cause premature EGR valve failure. The contaminants in bad fuel can lead to increased carbon buildup and other issues.

Lack of Maintenance

Regular maintenance is crucial for the health of an EGR valve. Without it, carbon deposits may not be cleaned regularly, leading to the valve getting stuck open or closed.

Faulty Parts

Faulty or failing parts in the EGR system can lead directly to the valve itself failing. This is because the EGR valve relies on these parts to function properly.

Manufacturing Defects

If the EGR valve or its related components are not manufactured to the correct specifications or quality standards, this could lead to premature failure of the valve.

Extreme Operating Conditions

Operating a vehicle in extreme conditions, such as very high or very low temperatures, or using it for heavy-duty tasks, can put extra strain on the EGR valve and lead to early failure.

Can a Bad EGR Valve Cause Engine Damage?

What Causes EGR Valve Failure

Yes, a bad EGR valve can cause engine damage, as it can alter the vehicle’s air-fuel ratio, cause the engine to overheat, leading to a buildup of heat within the engine, and even cause serious damage such as warped heads and cracked blocks from overheating if left unchecked for too long.

EGR is an emission control device that is used in engines to reduce the amount of nitrogen oxide released into the atmosphere and reduce the combustion temperature by redirecting a portion of the exhaust gases into the engine inlet.

When the EGR valve fails, i.e. gets stuck in an open or closed position, your vehicle will exhibit certain changes.

When the EGR valve gets stuck in an open position, more carbon will be drawn into the engine which causes the engine to basically starve for fresh air. This causes the air intake sensors to miscalculate false air intake and decrease fuel injection even further.

With the air-to-fuel mix ratio thrown off balance due to the EGR valve stuck open, your engine will run rough, vibrate, and shake which can cause engine damage.

When the EGR valve is stuck in a closed position, the opposite happens. In this case, more fresh air goes into the engine which increases the combustion temperature. The increase of the temperature in the combustion chamber can make a knocking sound and often results in engine overheating says Turbo Packs.

How Long Should an EGR Valve Last?

An EGR valve is designed to last for up to 10 years or 50,000 miles. However, the durability of an EGR valve is greatly affected by the way you drive your vehicle. This is mainly because the EGR valve is usually activated between 1000 RPMs and 2000 RPMs. If you drive your vehicle in heavy traffic, the EGR valve will be activated most of the time, causing it to fail sooner.

The EGR valve has a mission to reduce the number of harmful toxins being released into the atmosphere and to reduce the temperature of the combustion chamber. This is accomplished by allowing some of the exhaust gases to be redirected back through the engine’s intake to be burned off again in the combustion process.

When the EGR valve opens, it redirects hot exhaust gases back into the combustion chamber. This is done only at lower speeds because hot air is less dense than fresh air and results in less engine power. This means that if you drive your vehicle at lower speeds with 1000 to 2000 RPMs, the EGR valve will constantly be activated. The more the EGR valve is activated, the less time it will last.

You can increase the longevity of the EGR valve by driving mainly on highways instead of in heavy city traffic. Another thing that you can do to increase the durability of the EGR valve is to clean it occasionally. You can either clean the EGR valve without removing it, or you can remove the EGR valve, inspect it, and clean it.

If you decide to go with the second method and actually remove the EGR valve, make sure to inspect it. Check the condition of the EGR valve. There are some high-quality EGR valves on

Will a Bad EGR Valve Throw a Code?

Yes. A bad EGR valve can throw a couple of codes including P0401 if the EGR valve is not flowing enough recirculated exhaust gases when ordered by the ECM, or a P0402 code if the EGR valve is flowing too much-recirculated exhaust gases into the intake manifold.

The purpose of the EGR valve is to open up and recirculate part of the exhaust gases back into the intake manifold. These exhaust gases help reduce the temperature of combustion. NOX is formed in high temperatures so reducing the temperature of combustion, reduces the NOX formation.

When it comes to symptoms of a bad EGR valve, it can go two different ways; Stuck open EGR valve, or stuck closed EGR valve. In both cases, a bad EGR valve will throw a check engine light on the dashboard, and an error code if you scan your vehicle with an OBD scanner.

In fact, a bad EGR valve can throw a total of 10 codes:

OBD-II Error CodeMeaning
P0400EGR valve not flowing recirculated exhaust gases when ordered by the ECM
P0401EGR valve not flowing recirculated exhaust gases when ordered by the ECM
P0402EGR valve flowing too much-recirculated exhaust gases into the intake manifold
P0403EGR circuit has malfunctioned
P0404EGR valve or sensor is out of specification range
P0405EGR sensor is operating below the specification range
P0406EGR sensor A runs at a high circuit voltage
P0407The EGR system is facing a voltage problem
P0408PCM has detected an issue with the EGR system
P0409The EGR sensor A circuit has malfunctioned

Can You Run a Car Without an EGR Valve?

From a mechanical point of view, yes, you can run a car without an EGR valve. The strength of the engine would be significantly reduced, the vehicle could shake at idle, misfire, or not start at all. However, from a legal point of view, driving a vehicle without an EGR valve is considered illegal in most states.

EGR valves are anti-pollution devices that are designed to recirculate some of the exhaust gases back into the combustion chamber when ordered by the vehicle computer.

Before EGR valves were invented, older vehicles had catalytic converters that were used to burn pollutants. However, they got too hot because while burning the pollutants, sometimes they burn the unburned hydrocarbons which created extra heat.

So, the engineers got together and created the EGR valve. Now, the EGR valve recirculates inert gas with very little oxygen back into the combustion chamber that burns at lower temperatures.

Driving with a faulty EGR valve or without an EGR valve is possible. You would definitely feel a difference while driving. Many car owners report that their cars started to shake at idle. They saw a check engine light on their dashboard and excessive vibrations. Some couldn’t even start their vehicles in the first place.

But, let’s say you do start your vehicle without an EGR valve. Because you don’t have an EGR valve, there is no anti-pollutant device on your vehicle. If the EGR valve is not recirculating exhaust gases and lowering the temperature, you are now polluting the atmosphere with NOX. This is considered illegal in many states, and will definitely get you to fail the emissions test.

How Do You Prevent EGR Valve Problems?

  • Regularly service your vehicle to ensure all parts, including the EGR valve, are in good working condition.
  • Use high-quality fuel to reduce the buildup of carbon deposits in the EGR valve.
  • Clean the EGR valve regularly to prevent soot and dirt accumulation.
  • Install a catch can system to trap oil and soot before they reach the EGR.
  • Consider using fuel additives designed to clean and maintain the EGR valve.
  • Ensure the engine is running at the correct temperature to prevent excessive carbon buildup.
  • Replace the EGR valve as per the manufacturer’s recommended schedule.


Q: What is an EGR valve?

A: The EGR valve, or Exhaust Gas Recirculation valve, is a component of an internal combustion engine that reduces harmful emissions by recirculating a portion of the exhaust gases back into the engine cylinders.

Q: How do I know if my EGR valve is failing?

A: Some common signs of a failing EGR valve include rough idle, engine hesitation or misfiring, decreased fuel efficiency, increased emissions, and the illumination of the check engine light.

Q: Can a faulty EGR valve cause engine damage?

A: Yes, a faulty EGR valve can potentially cause engine damage if not addressed promptly. It can lead to increased internal engine temperatures and the accumulation of carbon deposits, which can result in reduced engine performance and longevity.

Q: Can I drive my vehicle with a bad EGR valve?

A: It is generally not recommended to drive a vehicle with a faulty EGR valve for an extended period of time. While it may still be possible to drive the vehicle, doing so can lead to further damage to the engine and could result in costly repairs.

Q: How much does it cost to replace an EGR valve?

A: The cost to replace an EGR valve can vary depending on the make and model of your vehicle, as well as the labor costs associated with the repair. On average, the cost can range from $150 to $400.

Q: Can I clean the EGR valve instead of replacing it?

A: In some cases, it may be possible to clean the EGR valve to restore its functionality. However, this is not always a permanent solution, and if the valve is heavily damaged or corroded, replacement may be necessary.

Q: How often should the EGR valve be inspected?

A: The frequency of EGR valve inspections can vary depending on the manufacturer’s recommendations and the specific vehicle. It is generally recommended to have the EGR valve inspected during routine engine maintenance or if any symptoms of failure are present.

Q: Can a clogged EGR valve cause poor fuel economy?

A: Yes, a clogged EGR valve can disrupt the proper air-fuel mixture in the engine, leading to decreased fuel economy. This is because the valve may not recirculate the correct amount of exhaust gas, affecting combustion efficiency.

Q: Can I remove the EGR valve to improve engine performance?

A: It is not recommended to remove the EGR valve with the intention of improving engine performance. The EGR valve plays a critical role in reducing emissions and its removal can lead to increased pollution and potential legal repercussions, depending on your location’s emissions regulations.

In Conclusion

EGR valves are subject to a range of wear and tear caused by dirt build-up, corrosion, and vacuum leaks.

Over time, these issues can cause the valve to become blocked or stuck, which can lead to increased emissions and decreased engine performance.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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