An EGR valve, or exhaust gas recirculation valve, is an essential component in many internal combustion engines that helps to reduce nitrogen oxide (NOx) emissions. NOx is a particular air pollutant that can put up with smog and respiratory problems.
But what happens if the EGR valve fails? How do you comprehend your vehicle’s EGR valve is faulty or failing? What are the signs? What is the fix? Be with me throughout this detailed guide to know the explanations for all these questions. Read on to learn more!
How Does an EGR Valve Work?
You might know that your car’s engine needs air from outside to run properly, mostly containing 80% nitrogen and 20% oxygen. When fuel and air mix and burn inside the engine, it gets hot, reaching extremely high temperatures.
At these high temperatures, nitrogen in the air combines with other elements to form harmful pollutants called oxides of nitrogen (NOx). NOx can cause respiratory problems in humans.
To reduce the amount of NOx your car emits, exhaust gases must be cooled down before they are released into the air. The exhaust gas recirculation (EGR) valve comes in at this exact spot.
The exhaust gas recirculation (EGR) valve allows some of the exhaust gases to be redirected back into the combustion chamber of the car’s engine. This lowers the temperature inside the engine, which helps prevent the formation of NOx emissions.
Simply put, an EGR valve is a simple device to control the flow of exhaust gases. The moment it is open, exhaust gases can pass via the EGR system, which helps reduce emissions. When it is closed, exhaust gases cannot pass through the EGR system.
The EGR valve remains closed when you turn on the car’s engine. As you drive and the engine warms up, the valve gradually opens to allow some exhaust gases to recirculate. But when you stop or slow down, the valve gradually closes again.
And this happens continuously throughout your journey to ensure that exhaust gases are only recirculated when the engine is at the right temperature. This allows your car to maintain fuel efficiency and emit fewer pollutants.
What Are the Types of EGR Valves?
There are primarily main types of EGR valves: vacuum-operated and electronically controlled EGR valves.
Vacuum-Operated EGR Valve
Commonly found in older vehicles, it is a simple system that relies on a vacuum to operate the valve. When the engine conditions are appropriate for EGR operation, the vacuum-operated EGR valve opens to permit the flow of exhaust gases into the intake manifold.
A computer-controlled solenoid usually regulates the vacuum that controls the valve, which helps determine when the valve should open and close.
Electronically Controlled EGR Valve
Most current-era cars use an electronically controlled EGR valve. It is managed by the vehicle’s engine control module (ECM), a computer that controls various aspects of the engine’s operation.
The ECM receives inputs from different sensors located across the vehicle to specify the optimal position of the EGR valve during your drive. These sensors provide information about engine speed, load, temperature, and other factors that affect the performance of the EGR system.
Based on this information, the ECM adjusts the position of the EGR valve to ensure the right amount of exhaust gases is recirculated at any given time.
Why Faulty EGR Valve Is an Issue?
A faulty EGR valve can create various problems with the functioning of the EGR system, which can negatively impact your vehicle’s performance and produce excessive pollutants.
It can lead to issues with the flow and operation of the EGR system, causing many performance-related problems, such as lower fuel efficiency, reduced acceleration, and decreased power.
Simply put, a faulty EGR valve can cause your car to produce higher levels of pollutants and may feel sluggish, need help to pick up speed and consume more fuel than usual.
What Are the Symptoms of a Faulty EGR Valve?
First of all, remember one thing, the symptoms of a faulty EGR valve may vary or may be similar to many other engine-related issues. However, the following are the most common symptoms of a faulty EGR valve.
When starting your vehicle or during brief stops, such as at traffic lights, you may experience a rough idle. This happens when the EGR valve is stuck open.
It sources a steady discharge of exhaust gases into the intake manifold. The influx of these gases disrupts the proper combustion process, leading to a rough idle.
A faulty EGR valve can result in the overall poor performance of your car. Whether the valve is stuck open or closed, its incorrect functioning can cause erratic performance, such as sluggish acceleration or a lack of power.
Increased Fuel Consumption
If the EGR valve is stuck open, it can raise fuel utilisation. When the valve remains open, the combustion chamber’s temperature lowers, preventing efficient fuel burning. As a result, your car becomes less fuel-efficient.
Frequent Stalling When Idling
When the EGR valve is constantly open, it can cause your car to stall frequently when idling. This is similar to the rough idle symptom, as the constant flow of exhaust gases disrupts the engine’s smooth operation at low speeds.
Smell of Fuel
A steady exhaust gases flow into the intake manifold, caused by a malfunctioning EGR valve, can produce a noticeable smell of fuel.
This occurs because not all the fuel burns at low revs due to the influx of exhaust gases. The increased emission of unburned hydrocarbon gases produces the fuel smell.
Engine’s Management Light Stays On
Your car’s engine management light may remain illuminated if the EGR valve is facing any problem. This can happen if the valve is either constantly closed or open.
However, it’s important to note that the EGR valve may start to degrade before completely failing, and the engine management system might not detect it until it fails completely. So, paying attention to other signs and symptoms is also important.
A malfunctioning EGR valve can lead to higher emissions. If the valve stays open, the lower temperature in the combustion chamber impacts complete fuel burning, resulting in more unburned hydrocarbon gases emitted from the tailpipe.
Conversely, if the valve is always closed, it can lead to excessive formation of NOx gases due to high temperatures in the combustion chamber.
Knocking Noises from the Engine
Constant closure of the EGR valve can source knocking noises from the engine. This occurs since, at lower rpm, the fuel burns early due to the high temperature. It can lead to detonations or additional ignitions after the normal ignition, resulting in knocking noises.
Important Thing to Keep in Mind
Sometimes, the problems you experience with your engine’s performance may not only be caused by a faulty EGR valve but could also be linked to other system parts. This includes issues with spark plug wires, spark plugs, fuel pump regulators, fuel filters, or engine sensors.
The following are some common problems and their potential causes that may or may not happen due to faulty EGR valves.
A rough idle can also be attributed to factors other than the EGR valve. A vacuum leak, a defective ignition coil, or problems within the ignition system might cause it.
Increased Hydrocarbon Emissions
If you notice increased hydrocarbon emissions, it may be due to other issues rather than just the EGR valve. Possible causes include a leaking fuel injector, incorrect injection timing, low cylinder compression, or a malfunctioning oxygen sensor.
Increase in NOx Emissions
If there is a rise in NOx emissions, it may indicate problems beyond the EGR valve. Potential causes include a clogged fuel injector, a vacuum leak, a leaking head gasket, or low fuel pressure.
What Is the Solution for Faulty EGR Valve?
The solution for a faulty EGR valve depends on the severity of the issue. If the valve is simply stuck open or closed, it may be possible to clean it.
However, if the valve is corroded or damaged, it may require to be replaced. These are a few of the possible fixes for a faulty EGR valve.
Clean the EGR Valve
This can be done by removing and soaking the valve in a cleaning solution designed for EGR valves. Once the valve is clean, it should be reinstalled, and the engine should be tested to see if the problem is resolved.
Replace the EGR Valve
If the valve is corroded or damaged, it may require to be substituted. This is a fairly straightforward process that most car owners can do.
Reprogram the Engine Computer
In some cases, issues with the engine computer may induce a faulty EGR valve. If this is the case, the computer may need to be reprogrammed. This is a more complex procedure that a qualified mechanic should do.
How Much to Replace an EGR Valve?
Simply put, the cost to replace an EGR valve can range from £150 to £500 in total on average. This includes the price of the EGR valve and the labour costs associated with the diagnosis and replacement.
Note: These prices are simply estimates and can vary depending on various factors, such as the car model and the labour rates of the workshop.
Here’s a simplified breakdown:
Cost of the EGR Valve
A new EGR valve typically ranges in price from £90 to £350, depending on the car model. The exact cost will rely on the particular valve required for your vehicle.
The labour costs for replacing the EGR valve are typically higher than the expense of the valve itself. The total labour cost depends on the hourly rate of the workshop and the time required for the replacement. The average hourly rate in the UK ranges from £60 to £150.
The total price for replacing the EGR valve includes other factors, such as the diagnosis of the issue, the purchase of a new EGR valve, and the actual replacement process.