Symptoms of a Faulty EGR Valve

Symptoms of a Faulty EGR Valve – The EGR valve is a very essential car component in countries with strict regulations on vehicle emission. This is because the EGR plays a crucial role in regulating exhaust emissions. These regulations are strictly upheld in developed countries but not the same for some developing countries.

This article will explain everything you need to know about the EGR valve. Read on!

What is the EGR Valve?

The Exhaust Gas Recirculation valve, shortened, the EGR valve is a vehicle component that controls the emission level in modern vehicles. It helps keep exhaust emission within allowable levels.

The component is mostly found in modern fuel-powered vehicles and it reduces engine emissions by recirculating some of the exhaust emissions back into the engine. Such recirculation allows complete combustion of the fuel. It also reduces toxic substances like nitrogen oxide (NOx).

Over the years, it has been proven that cars have contributed immensely to environmental pollution and climate change due to harmful emissions into the atmosphere.

In response to this, the government proposed the addition of an EGR valve to every vehicle manufactured recently to curb air pollution as a result of exhaust emission.

How does the EGR Valve Work?

The air in the environment is trapped by the intake manifold of a vehicle.

The air itself is made up of about 20% oxygen and 80% nitrogen with other components present in smaller proportions.

Oxygen reacts with the fuel at a high temperature, about 2500°F inside the engine, while nitrogen burns to form an increased rate of NOx emissions. It then behoves the EGR valve to send the exhaust gases back into the combustion chamber to bring down the temperature and completely suppress the formation of NOx.

When nitrogen has been exposed to very high temperatures in the combustion chamber, it becomes reactive and creates harmful oxides of nitrogen or NOx, which when emitted to the atmosphere causes pollution.

To reduce this, the EGR valve returns some portion of air into the intake system and seamlessly converts the chemical properties of the air that is sent back to the engine. The diluted mixture now burns slower, reducing temperatures in the combustion chamber by almost 150°C and reducing oxides of nitrogen (NOx) for a cleaner and more efficient exhaust gases.

The EGR valve has two major settings: open and close.

The EGR valve remains closed when the engine is starting up. While it idles or at a low speed, only a little amount of oxygen is required and at this point, the valve begins to open little by little.

The valve can open up to 90% when it’s idle, but as more power is required, for instance, during full acceleration, the EGR valve closes to ensure more oxygen stays in the cylinder.

What are the Types of EGR Valve?

There are many types of EGR valves.

Older vehicles made use of vacuum-operated valves while newer vehicles are making use of electronically-controlled valves.

The types of EGR valve can be categorised into the following.

Diesel high-pressure EGR valves

The diesel high-pressure EGR valves diverts the high-flow and high-soot exhaust gases before it enters the diesel particulate filter.

The soot combines with oil vapour to create sludge and the exhaust gas is returned to the intake manifold through a pipe.

Diesel low-pressure EGR valves

The diesel low-pressure EGR valves re-channel the exhaust gas after it has passed through the diesel particulate filter.

The gas here has a lower flow and is almost soot-free. The gas is returned to the inlet manifold through a pipe.

Gasoline EGR valves

The gasoline EGR valves works just like the high-pressure diesel valves.

The vacuum created by the cylinder depression returns the exhaust gases into the engine and this flow is regulated by the opening and closing of the EGR valve itself.

Vacuum-operated EGR valves

The vacuum-operated EGR valves utilizes a vacuum solenoid to carry the vacuum to the diaphragm which in turn opens and closes the EGR.

It also includes a feedback sensor that signals the electronic control unit (ECU) of the valve’s position.

Digital EGR Valves

They have a solenoid or stepper motor with a feedback sensor in some cases.

The Digital EGR valve receives a pulse width modulated signal from the ECU to regulate exhaust gas flow.

Symptoms of a Faulty EGR Valve
EGR Valve

Symptoms of a Faulty EGR Valve

Low fuel economy

A bad EGR valve will cause a drop in fuel economy because the temperature inside the combustion chamber is quite low.

This implies that the fuel inside it does not ignite effectively or does not burn at the optimal temperature, making it less efficient.

Increased fuel consumption occurs when the EGR valve is constantly open due to failure.

Fuel odour

When your EGR valve is failing, your engine burns more fuel and releases hydrocarbons.

Since there is a constant flow of exhaust gases in the intake manifold and the fuel burns unusually, the amount of hydrocarbon released from the tailpipe increases and produces a fuel odour.

Engine performance reduces drastically

If your EGR valve is stuck open or closed, it will reduce the performance of your car.

You will experience difficulties while accelerating, a decreased fuel economy or sputtering.

Improper functioning of the EGR valve causes the erratic performance of your engine and the car as a whole.

Engine rough idling

A rough idle when starting your car occurs when the EGR is constantly open and there is a continuous flow of exhaust gases into the intake manifold.

When the valve is in the open position, it will allow too much exhaust gases into the combustion chamber which will throw off the air/fuel mixture and cause the engine to idle roughly.

Check engine light comes on

Your check engine light illuminates sometimes as a result of a faulty EGR valve.

An electronically operated EGR valve receives data from the engine control module (ECM) which can also illuminate the check engine light.

Knocking sound from the engine

If the EGR remains constantly closed, you will hear a knocking/clunking sound from the engine because at a low RPM, fuel ignites quickly when it meets a high temperature.

The vehicle produces more emissions

If your EGR valve is faulty, your car will produce more emissions and would likely fail the emission test.

When the valve is stuck open, it lowers the temperature of the chamber and prevents all the fuel from burning which implies that there will be an increased flow of unburned hydrocarbon gases emitting from the tailpipe.

However, if the valve is closed, the temperature in the combustion chamber remains high which allows the excessive formation of NOx gases.

Failed emission test

If you find yourself in a situation where you have to carry out an emission test in your car every 6 months, it might be an indicator that there is a problem with your EGR valve.

If you fail the emission test, then it is important to have your EGR valve checked.

Causes of EGR Valve Failure

There are several causes of EGR valve failure.

However, the three most common causes include:

Clogged EGR pipe

The EGR system routes exhaust back to the engine through the EGR pipe.

This exhaust flowing through the pipe contains soot and other contaminants that tend to build up and clog the walls of the EGR pipe.

These deposits get thick over time and interrupt the free flow of exhaust gases causing the EGR system to suffer from an insufficient flow which will, in turn cause the temperature of the engine to rise to abnormal levels.

You can unclog the EGR pipe by detaching it from the engine and spraying the inside with a carburettor cleaner. This will loosen up any deposit on the pipe. From there, you can brush it away with a metal-bristle brush.

Faulty temperature sensor

Another common source of EGR failure is the temperature sensor.

If the EGR system temperature goes bad, there will be a faulty reading as a result of carbon build-up causing your valve to malfunction.

The EGR valve usually ensures there is fuel efficiency by regulating temperature and pressure inside the engine. To maintain a proper temperature, the EGR only opens up at certain times.

The EGR valves depend on information it receives from the temperature sensor to know the proper time to open up. As the engine temperature rises, the EGR valve opens progressively. When the engine has equally cooled down, the valve closes again.

Sticky EGR valve

The contaminants that clog up the EGR pipe can as well clog the valve itself. With time, these contaminants make it difficult for the valve to open and close when it is supposed to.

The valve can be stuck in a somewhat closed or open position which affects the performance of the EGR system.

If the EGR valve sticks in the closed position, it will prevent exhaust gases from entering the engine and the engine temperature will rise, resulting in knocking noises from the engine.

If the EGR valve sticks in the open position, it allows too much exhaust into the engine which will cause your engine to rough idle more often or cause it to stall.

Other causes of EGR valve failure include:

  • problems with the differential pressure feedback sensor.
  • problems with the EGR vacuum switching valve.
  • clogged catalytic converter.
  • electrical problems with the EGR valve control circuit.
  • leaks in the intake manifold.
  • defective vacuum solenoid.

What Happens When You Ignore a Faulty EGR valve?

If you ignore a faulty EGR valve, the problem will become more complicated and quite difficult to handle.

After reading through the list of symptoms, you will notice that it is a bad idea to ignore a faulty EGR valve. A faulty EGR valve will make you have a bad driving experience.

In some countries, your vehicle will fail the emission test which implies that you are not allowed to legally drive your vehicle around in those places.

Benefits of A Good EGR Valve

Driving a car with a good EGR valve is beneficial to the driver, the vehicle and the environment. It lessens the negative impact of driving on the environment.

Other benefits of a good functioning EGR Valve include:

Fuel economy

If the EGR valve is clogged, there will be improper combustion and more fuel will be consumed.

To prevent this and maintain the proper functioning of your engine and less fuel consumption, the EGR valve should be in a good condition.

Increased engine life

The EGR contributes to the longevity of the engine because it helps to reduce the temperature of the engine.

The EGR keeps the cylinder at a low temperature leading to lower thermal stress and longer life.

Fewer emissions

The EGR valve is meant to reduce emissions from the engine, but if it is faulty, it fails to perform this task leading to environmental pollution while driving.

If the EGR valve is faulty, the emissions will be too high and it will fail the emission test but if it is in good condition, it will reduce the emissions.

Symptoms of a Faulty EGR Valve
EGR Valve cleaning

How to Clean the EGR Valve

All you need to do when your EGR valve is dirty is to clean it.

Cleaning the valve is quite easy and it will prevent serious engine damages, expensive repairs, and engine performance issues.

To clean the EGR valve, you will need a ratchet, ratchet extension, adjustable wrench, socket set, dull scraper, goggles, acid-resistant gloves, new EGR valve gasket (if necessary), valve or carburettor cleaner.

To begin the cleaning process, you put on your acid-resistant gloves and goggles/safety glasses, then follow the procedures here.

  • Spray carbon deposits with carburettor cleaner and quickly wipe it off plastic parts and electrical components to prevent damages.
  • Scrub the carbon build-up off using the dull scraper and pipe cleaning brush. Next, use a soft brush to remove the carbon deposits and wipe it off with a clean rag. You can repeat this until you are sure you’ve completely removed all carbon deposits. Avoid sealing and mounting surfaces so that you won’t cause exhaust gas leakage.
  • If there is a rock-hard carbon build-up, soak the valve in the cleaning agent for some minutes but ensure electrical components, plastic areas and electronic components don’t get in contact with the cleaner or they will be ruined.
  • Repeat the above procedure if the carbon deposit is stubborn. Though, the valve could be soaked in the cleaner overnight, but this is risky because the corrosive chemicals in the cleaner can damage the valve.
  • If there are still carbon deposits in the intake manifold, you can clean it up with the EGR valve cleaner. Follow the instructions on the product’s package or you can take your car for carbon cleaning service.
  • Once all the carbon build-up has been cleaned including all passages, reassemble all components and check your car to ensure that the symptoms associated with it have disappeared.

How to Test the EGR Valve

Knowing how to test the EGR valve will save you money, time and some stress.

When you’ve used your vehicle for some time, carbon build-up, or leaks that might occur will cause your EGR valve to start misbehaving leading to poor performance of the engine.

Here are simple procedures on how to test the EGR valve:

1. Locate the EGR valve

Look out for a round, thick, metal disc of about 3 inches in diameter. Sometimes it is found on the top of one side of the engine.

A thin vacuum line is usually connected on top of the valve. This usually depends on your vehicle model because different cars usually have different configurations.

If you can’t locate the EGR valve for your car model, you should consult the service manual of your car or an auto parts retailer on the web.

2. Test the valve stem manually

The valve metal disc is made up of a diaphragm, spring and plunger which helps to maintain the valve in a closed position.

When functional, an increase in vacuum pulls on the diaphragm overcomes the spring pressure to open up the valve.

To test the valve stem, you do the following;

  • Push on the diaphragm by sticking a finger through one of the openings of the EGR valve if you can assess it.
  • If the diaphragm doesn’t move when you apply finger pressure, inspect the passages of the EGR valves for carbon deposits that may restrict plunger movement. If this is not the case, it means the unit has failed.

3. Test the EGR valve diaphragm condition

The valve diaphragm may start leaking exhaust gases as a result of wear and tear of the mechanism. You’ll also need to inspect the diaphragm to know its condition using the following measures.

  • Block the wheels, apply the parking brake and start the engine.
  • Spray some carburettor cleaner through the underside openings and towards the diaphragm. Do this with a thin straw inserted into the tip of the carburettor cleaner.
  • As you spray the carburettor cleaner into the valve, if the diaphragm is leaking, the engine’s RPM will increase which requires you to replace the valve.

4. Test for stem movement

You test for stem movement through the steps here.

  • Put on the engine and let it idle for some minutes to bring it up to the normal operating temperature.
  • While the engine is idling, rev it up to about 2,500 RPM.
  • Use a small hand mirror to watch the valve diaphragm movement or you can watch it on your own.
  • If the stem diaphragm is not moving, disconnect the thin vacuum hose from the top of the valve then place your finger on the opening of the hose you disconnected.
  • Increase the engine RPM as you did earlier and you will feel a slight pressure on your fingertip depending on the system type.
  • If you don’t feel any pressure then the problem is with the circuit that provides pressure to the valve. After doing this, reconnect the vacuum hose to the valve.

5. Test valve operation with a vacuum pump

To test the valve operation with a vacuum pump, do the following.

  • While the engine is idling at the normal operating temperature, disconnect the vacuum hose from the valve and plug it into the hand vacuum using a Philips-head screwdriver.
  • The hand vacuum pump should be connected to the EGR valve, then apply 15 in-Hg of vacuum to the valve.
  • While applying vacuum to the valve, check for diaphragm movement. At the same time, pay attention to engine idling. The engine should stall while you are doing this.
  • If the valve doesn’t hold the vacuum you’ve applied, or the plunger doesn’t move, you will need to replace the valve.
  • If you don’t notice any change in the engine’s idle operation but the diaphragm holds vacuum and the plunger moves then carbon build-up is blocking the passage of the EGR valve. If this is the case, you need to clean the EGR valve.

How to Fix a Faulty EGR Valve

The steps here can help you make this easier.

  • Remove the engine cover, loosen the electrical cable on the valve and then remove the electrical connections to check for damages.
  • Remove the fastening screws to check for valve damage, corrosion, or carbon build-up.
  • Clean the EGR valve mounting surface very well then fix a new valve and gasket. Remove any carbon particle from the EGR supply port.
  • Place the EGR valve with the bolt holes and gasket then reattach it to the housing.
  • Tighten the fasteners to the recommended torque setting and once it is firmly seated, connect the vacuum lines and electrical connections.
  • In the end, use a diagnostic scan tool to reset the engine management light and check for other errors. Also, ensure that the malfunctioning indicator light has been taken care of. Finally, take your vehicle for a road test.

Cost of Replacing an EGR valve

If the EGR valve is damaged or worn out due to overuse, replacement remains the only option.

The cost of an EGR valve is relatively cheap and can be as low as $150 or about $500 for both parts and labor depending on the model of your vehicle.

Some EGR valve problems may just require cleaning it with a throttle body cleaner.

How to Troubleshoot an EGR Valve

While troubleshooting the EGR valve, it is always important to follow the procedure in the service manual, because there are different types of EGR valves.

Below are generic steps that you can use to troubleshoot your EGR valve.

  • Read fault codes on an electronically controlled EGR valve using a diagnostic tool.
  • Ensure that all electrical connections and vacuum lines are in place.
  • You will need a vacuum gauge to check the vacuum supply hose for vacuum at 2000 to 2500 RPM. If the vacuum is at the normal operating temperature, it will not suggest a loose hose, faulty ported vacuum switch, or a faulty vacuum pump.
  • Check the vacuum solenoid while the engine is still running. Activate the solenoid with a scan tool on the electronically controlled EGR valves and inspect the vacuum at the end of the pipe. If the solenoid is stuck in the open or closed position, has a corroded electrical connection or loose wire, EGR operation will be affected. It is important to identify the problem before replacing the valve.
  • Check the movement of the valve stem at 1500 to 2000 RPM if possible. If the valve is functional, the valve stem will move, if otherwise, there is a problem with the valve.
  • Use a hand vacuum pump to apply vacuum directly to the EGR valve. You can also use a scan tool depending on the type of EGR valve. Should there be no change in the idle quality, then the EGR is faulty or there are obstructions in the passage. If the engine stalls or has rough idles, the problem is from the control system.
  • Eject the EGR valve and check for carbon build-up, if available remove it carefully so that the diaphragm won’t be damaged.
  • Inspect the EGR passage in the manifold and clean up if there’s any clogging.

FAQs About EGR Valve

What can I do if my car has a bad EGR Valve?

If your car is showing symptoms of a faulty EGR valve as listed earlier, it is important to get your car checked by a qualified mechanic. You can also do it by yourself if you are conversant with some car components and repair tips. Problems with the EGR can be diagnosed using the correct diagnostic equipment.

How long can I drive with a faulty EGR Valve?

You can drive your vehicle with a faulty EGR valve but you will experience symptoms like engine check light illumination, knocking sounds in the engine, or rough idling. Also, while driving, your vehicle must be eco-friendly, the EGR valves reduce emissions into the atmosphere by recirculating exhaust gases. Due to this reason, it is not advisable to drive with a faulty EGR valve for too long. You should get it fixed as soon as possible if it is faulty.

How often do EGR Valves go bad?

Proper maintenance of the EGR valve is necessary if you want it to last for a longer time. An average EGR valve lasts for approximately 10 years and can last a bit longer if properly maintained. EGR valves don’t go bad often except when neglected. Carbon or soot build-up can clog the EGR valve and limit its functionality.

How often does an EGR Valve need to be replaced?

EGR valves may last for up to 100,000 miles, and sometimes less than that. It is advisable to replace the EGR valve every 40,000-50,000 miles. The lifespan of the EGR valve is sometimes determined by the owner’s maintenance and driving pattern. When your valve has been put to use for a long time, it is important to access it to know if it is in good condition. From there, you can repair or replace it if necessary.

Can a bad EGR Valve cause overheat?

When the EGR valve restricts the flow of gas through the EGR cooler due to clogging or carbon build-up, overheating will occur. Since clogging will obstruct the release of NOx into the atmosphere, the temperature of the engine can increase to dangerous levels causing your engine to heat up.

How can I prevent problems with my EGR valve?

You can prevent problems with the EGR valve by carrying out routine checks and maintenance on the valve. EGR valves become stuck open or closed as a result of carbon build-up, soot particles, dirt, and deposits from fuel. To prevent EGR problems, it is important to clean this up with a recommended valve cleaner. Cleaning it will improve the longevity of the EGR valve.

Can a bad EGR Valve cause a misfire?

If there is a vacuum leak in your EGR system, it will cause your engine to misfire from time to time. At times, the EGR valve does not give a timely response to the Electronic Control Unit (ECU) which implies that the valve could stay open or closed longer than supposed which will cause a vacuum leak in the manifold that will lead to engine misfiring.

Can the EGR valve be cleaned?

Yes! The EGR valve can be cleaned. Cleaning the valve will help solve your engine performance issues which is caused by clogging of the valve or passages. You can clean the EGR valve by following the procedures listed earlier in the article.

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