Top 13 Bad EGR Valve Symptoms And How To Test

The EGR valve is used in the exhaust flow of your engine. It has a bad design which leads to premature failure. If you have bad EGR valve symptoms, then this article will help you solve the problem. In this post, we’ll explain what all the EGR valve symptoms are and how you could get them.

What Is An EGR Valve?

The exhaust gas recirculation (EGR) valve is a device that’s used to control the air-to-fuel ratio in your engine. A component of the emissions system aids in the reduction of hazardous emissions from the vehicle’s exhaust.

The EGR valve may be used to restore some exhaust gas to the intake manifold. This reduces combustion temperatures and produces less nitrogen oxide (NOx).

What Is An EGR Valve

The EGR valve can also be used to achieve lean burn, which is when a fuel mixture has less air than it needs for complete combustion. For example, if a car has an EGR valve and you’re driving at high speeds on the highway, it might temporarily switch from rich mode to lean mode so that it can maintain power at high RPMs.

How Does An EGR Valve Work?

The exhaust system includes the EGR valve. Between the intake and exhaust manifolds is a tiny tube called a catalytic converter. This part’s function is to control the engine’s output of exhaust gas. The EGR valve aids in the reduction of noxious byproducts.

The engine uses oxygen in its fuel mixture to burn gasoline or diesel fuel, but it also produces carbon monoxide and other pollutants as byproducts. These pollutants are harmful to the environment and can cause health problems for people nearby if they’re not properly treated before being released into the air.

EGR Valve Function

The EGR valve is a device that allows exhaust gas to be recirculated back into the cylinder. It is controlled by the PCM (Powertrain Control Module) and is activated when needed.

The EGR valve prevents unburned fuel from entering the combustion chamber. This unburned fuel would cause carbon build-up on the valves, piston crowns, and cylinder walls. Carbon build-up can also create a lean condition at idle speeds since it reduces the amount of oxygen available for combustion.

The EGR valve is activated during cold starts and when starting a vehicle after it has been sitting for long periods of time without being driven. The purpose of this is to reduce emissions by burning off any excess fuel in the engine’s cylinders before it enters the combustion chamber.

EGR Valve Location

EGR valves are located in the exhaust manifold. They are designed to reduce the number of nitrogen oxides (NOx) produced during combustion by diverting a small portion of the exhaust gas back into the engine. This reduces combustion temperature and pressure, as well as NOx production.

The PCM is in charge of operating the EGR valve (Powertrain Control Module). The PCM uses information from various sensors to determine whether or not the engine is operating under conditions where it would benefit from EGR operation.

If so, it opens the EGR valve allowing exhaust gas to enter the intake manifold. This reduces combustion temperature and pressure, as well as NOx production.

Bad EGR Valve Symptoms

The Engine Is Idling Rough

The Engine Is Idling Rough

When the EGR valve goes bad, it can cause your engine to idle rough. When this happens, you may notice that the engine hesitates or stalls when you come to a stoplight or stop sign. You may also notice that the engine shakes while idling or that it doesn’t turn over as easily as usual when starting up.

Poor Performance

Poor Performance

If you notice a decrease in your vehicle’s performance, this could be due to a faulty EGR valve. It may also be accompanied by knocking noises coming from your engine and an increase in hydrocarbon emissions.

Increased Fuel Consumption

Increased Fuel Consumption

In addition to a rise in consumption, there is a decrease in mileage. Engine stalls often with the CEL illuminated. There is a check engine light on, and the vehicle keeps stalling. There are knocking noises coming from the engine which can be heard when you start your car or when you accelerate.

Frequently Stalls When Idling

Frequently Stalls When Idling

The car often stalls while idling, especially when it’s cold outside or when it hasn’t been driven for a while. The engine management light stays on and the car keeps stalling. There are knocking noises coming from the engine which can be heard when you start your car or when you accelerate.

Fuel Smell

Fuel Smell

Exhaust gases entering your car through the intake manifold will smell like rotten eggs if your exhaust system has an issue. This could be caused by a faulty EGR valve or an oxygen sensor failure.



An overheating engine can be caused by a number of factors including low coolant levels, bad thermostats, oil pressure issues, or clogged radiator fins. However, if you’re experiencing overheating along with any other symptoms mentioned above, then it’s likely due to a faulty EGR valve.

The Engine Management Light Is Constantly Illuminated

The Engine Management Light Is Constantly Illuminated

After you start your automobile, the engine management light remains illuminated. This can be due to a bad EGR valve or an oxygen sensor failure. If the light stays on after you start your car, it means that your engine is not “learning” how hard it needs to work and adjust its operation based on driving conditions.

Car Produces More Emissions

Car Produces More Emissions

If you notice an increase in hydrocarbon emissions and NOx levels coming from your car, it could mean that your EGR valve is failing or has failed completely. An increase in emissions can also cause problems with your engine’s performance and fuel economy.

Hear Knocking Noises Coming From The Engine

Hear Knocking Noises Coming From The Engine

If your engine is making knocking sounds, an EGR valve problem may be to blame. If you notice these noises when driving up hills or accelerating quickly, this could be an indication that the valve needs to be replaced immediately.

Increased Hydrocarbon Emissions

Increased Hydrocarbon Emissions

When the EGR valve is stuck open or closed, it can allow raw fuel to pass through without burning or cleaning up properly. This causes increased emissions of hydrocarbons as well as carbon monoxide and nitrogen oxides.

Your Fuel Economy Lowers

Your Fuel Economy Lowers

An exhaust gas recirculation system is designed to improve fuel economy and lower emissions by reducing the amount of unburned fuel that gets through the intake manifold into the combustion chamber. If your EGR valve doesn’t work properly, you’ll see a dip in your fuel economy and an increase in harmful emissions.

The Check Engine Light Stays On

The Check Engine Light Stays On

One of the most common bad EGR valve symptoms is when the check engine light remains on after being reset. This happens because the computer has detected a fault code related to the EGR valve itself or its operation. If you’re experiencing this problem, take it to a mechanic who can diagnose your car’s emissions system and replace any faulty parts.

An Increase In NOx

An Increase In NOx

NOx, also known as nitrous oxide, is one of several harmful chemicals released by your engine during combustion. High levels of NOx can contribute to smog and acid rain, but they also cause premature degradation of catalytic converters and oxygen sensors. If your vehicle has been experiencing these issues lately, they may be caused by a bad EGR valve.

Types Of EGR Systems

Vacuum-Controlled EGR System

This is one of the most common types of EGR systems in use today. They use vacuum pressure to control when the exhaust gases flow back into the intake manifold. This type of system works well because it doesn’t require any additional sensors or electronics to work properly.

However, they can be sensitive to engine load changes and may not work properly if there’s too much carbon buildup in your engine’s valves or piston rings.

Electronic-Vacuum-Controlled EGR System

Electronic vacuum-controlled EGR systems use a solenoid valve to control exhaust gas recirculation based on manifold vacuum. The solenoid valve opens when an electronic control module detects that the engine has reached a specified load level.

The exhaust gas then passes through the intake manifold and into the cylinder head. The exhaust gas mixes with the incoming air and cools down the combustion process, which reduces nitrogen oxide (NOx) emissions.

Radical Design

A radical design uses a unique design to add more oxygen to your engine’s exhaust stream to reduce NOx emissions. This system works by using an injector that injects additional fuel into your exhaust system before it exits the engine.

This fuel burns in the hot exhaust gases and creates more heat, which creates more oxygen so that less fuel needs to be burned during combustion. The fact that you’re burning less fuel means that you’re emitting less CO2 into the atmosphere as well as reducing NOX emissions from your vehicle!

Digital EGR System

This type of EGR system operates similarly to a radical design but uses digital sensors instead of mechanical sensors to detect when more fuel is needed or when it’s time to save fuel by blocking some airflow through the manifold via an electronically controlled solenoid valve.

This type of electronic system also allows for better control over how much exhaust gas returns to your engine’s cylinders, which improves engine performance while maintaining stable emissions levels at all times.

How To Test An EGR Valve?

Inspect For Diagnostic Trouble Codes

check for diagnostic trouble codes (DTCs)

The first thing you should do is check for diagnostic trouble codes (DTCs). If your vehicle has a code that says “EGR System” or something similar, this is a good sign that there is a problem with your EGR valve.

If no DTCs are present, it doesn’t necessarily mean that your EGR valve is working fine; it may just be that there wasn’t enough exhaust flow to trigger the sensor.

Conduct A Visual Check

The next thing you should do when testing the EGR valve is conducted a visual check. First, remove your engine cover and then locate this valve itself.

Conduct A Visual Check

The EGR valve is usually located near the exhaust manifold and has two hoses attached to it: one that goes into the intake manifold and one that goes into the exhaust manifold. Inspect both of these hoses for cracks or leaks. If either one appears damaged, replace it before proceeding with further testing.

Evaluate Your EGR Valve

Evaluate Your EGR Valve

Next up, you’ll want to evaluate your vehicle’s EGR valve itself by opening up the hood and taking a look at it from above. You’ll see a thin tube coming out of this part that leads down into one of the exhaust pipes where it connects to the engine block itself – this is where exhaust gases are routed through when they’re not being used in order to reduce emissions levels.

The Consequences Of Ignoring An EGR Valve Failure

Rough idle and difficulties starting the engine are two of the most prevalent signs of the EGR valve problem. However, these symptoms can also mean that there are other problems with your car such as a bad fuel injector or clogged catalytic converter.

If you ignore these symptoms, they will only get worse which could lead to serious damage to the EGR valve and your engine. The worst-case scenario is that your engine will stop working altogether and require expensive repairs or even replacement.

EGR Valve Replacement Cost

EGR valve replacement cost is the average price paid to a mechanic for labor and parts to replace the exhaust gas recirculation (EGR) valve in a vehicle. This valve maintains a constant quantity of oxygen in the engine by recirculating exhaust gas.

Whether you’re not sure if your EGR valve needs to be changed, have a look at our guide on diagnosing and repairing an EGR system. Between $500 to $1,500 is the usual cost for it replacement. This can vary depending on the type of car or truck you drive, as well as what kind of problems you’re experiencing with your exhaust system.

If your vehicle has other issues associated with the EGR valve, like clogged catalytic converters or failed emission tests due to excessive carbon buildup, then those will also affect how much you pay for repairs.


Suppose The EGR Valve Is Blocked. What Happens?

If your EGR valve is blocked or restricted, your vehicle will still run but at a loss of efficiency. You may notice that your engine runs hotter than normal and that fuel economy is lower than usual. Your car may also stall while driving at higher speeds or when accelerating.

What Causes An EGR Valve To Clog Up?

There are many reasons why an EGR valve can clog up, but they all come down to one thing: carbon deposits. These deposits are caused by a lack of proper engine maintenance, or even by using poor quality fuel at times.

If you do not clean your EGR valves properly or if you leave them clogged up for too long then they will eventually start causing problems with your car’s performance and efficiency, which may lead to costly repairs if left unchecked for too long.

Do EGR Valve Problems Affect Engine Performance?

Engine damage may be caused by a faulty EGR valve, yes. The EGR system recirculates exhaust gases from the intake manifold back into the engine.

This reduces the quantity of oxygen in the combustion chamber, which reduces the amount of carbon monoxide emissions. It also reduces NOx emissions by lowering combustion temperatures and increasing fuel economy.


So if you have any bad EGR valve symptoms, it might be best to order a new valve. However, if the EGR valve is working correctly and you still have problems with the car, you should concentrate on diagnosing other parts of the vehicle.

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