What is an egr sensor. EGR valve: what is it and in what cases will it need to be replaced

The number of cars on the world's roads is rapidly increasing. It is no secret that absolutely any vehicle equipped with an internal combustion engine poses a threat to the environment and human health.

About how to make the "iron horse" safer and more environmentally friendly, seriously thought in the 70s of the last century. It was then that the Exhaust Gas Recirculation system was developed, or as it is also called abbreviated - EGR.

The principle of operation of the EGR valve and what it is

Engineers and designers at leading automotive companies are working daily to improve the exhaust system of a car. During the operation of the internal combustion engine, exhaust gases are released into the environment, and it has long been a known fact that these gases contain a large amount of chemical compounds hazardous to health. Nitrogen oxide and nitrogen dioxide are considered the most harmful. The deviation of the concentration of these substances in the air from the norm provokes the occurrence of a number of diseases of the human heart and respiratory system.

The most rational way to reduce exhaust toxicity today is the use of the EGR system, the principle of which is exhaust gas recirculation. Ignition of a combustible mixture is possible only at high temperature and appropriate pressure. But, the whole catch is that it is precisely such conditions that are ideal for the formation of oxide, by combining oxygen with nitrogen.

The EGR valve allows you to send part of the exhaust gases to a portion of fresh air. This results in a decrease in the amount of oxygen in the mixture. A lean mixture needs a completely different temperature. For its ignition, 1400 or more degrees Celsius is no longer required.

Many drivers believe that the EGR valve reduces engine power, which adversely affects the technical performance of the car. It is for this reason that the system has not yet found proper distribution in the territory of the post-Soviet space. However, experiments and studies show the opposite: EGR does not reduce engine power, but increases it. Perhaps this is by reducing the number of detonations in the gasoline power unit.

Summing up the intermediate results, it can be noted that the USR valve allows:

• Improve the quality of fuel combustion;
• Reduce detonation in the engine;
• Reduce the amount of emissions of harmful substances;
• Provide auxiliary monitoring of the toxicity of exhaust gases.

It remains to be seen how the valve works. Today, modern cars are equipped with an ECU, which is a real "think tank". Based on the data received from various sensors (THA sensor, EGR level sensor), the control unit determines the optimal time for supplying exhaust gases to the intake manifold. Gas supply is possible due to a signal from the ECU, by which the solenoid valve opens, and conditions are created for vacuum in the pneumatic valve.

How equipment is cleaned

Due to poor quality fuel, premature failure of the EGR valve or another component of this system, such as a sensor, occurs. Already after 50 thousand kilometers traveled, the valve may break. There can actually be many reasons, but most often the breakdown occurs due to carbon deposits on the valve surface. Nagar violates the tightness of the system, and also has a negative impact on the quality of the signal coming to the computer.

Due to unstable operation, transmission failures are not uncommon. What should a driver do in such a situation? There is only one solution - regularly clean the EGR valve from carbon deposits. However, it is worth remembering that even regular maintenance of the system will not guarantee its smooth operation. Cleaning the valve from carbon deposits mainly occurs in several stages: placing the components in a light solvent, purging and flushing the channels.

Cleaning and the main signs of a system breakdown

At the first stage of cleaning, the recirculation channels are placed in a special cleaning solution. As a solution, many experienced drivers use a carburetor flush. At the second stage, the channels are purged with the help of special devices. It is recommended to do this work only with the valve open.

If it was not possible to clean the device, then in this case the only right decision would be to buy a new copy. Nagar is not the only reason for the failure of the USR. In the recirculation system, a number of other malfunctions occur related to the vacuum booster and thermal valves. The valve itself is considered the most vulnerable point in the system. In addition to clogging and soot, it is constantly affected by high temperature. For this reason, its periodic jamming in the open or closed position is possible.

The valve breaks down, the system ceases to perform its duties, the amount of nitric oxide in the exhaust gases exceeds all permissible levels. But this is not the only problem that arises from a broken EGR. The following symptoms are commonly referred to as malfunctions:

• At idle, unstable engine operation is noted;
• Diesel power drop;
• The manifestation of jerks of the vehicle at high speeds;
• Rapid wear of spark plugs and clogging of nozzles.

Is there an effective way to determine the cause of the breakdown and which component of the system failed? Scanning the system using electronic equipment is considered a quick and effective way to diagnose. Pleasure is not cheap, but even if it is possible to undergo a diagnosis, the result will not always be positive. The reason is that there is no sufficient information base on errors and there is no way to compare the actual and nominal characteristics of the element.

Some of the most common mistakes:

• USR system error - code P0400;
• EGR valve error - code P1403;
• Gas recirculation circuit error - code P0403;
• Error of valve functioning elements - code P0404.

Also, drivers often ask themselves: where is the EGR valve located? It is impossible to give an unambiguous answer to this question, since the location of this element in different brands of cars varies significantly. But, as a rule, the valve is always located near the main power unit of the machine. For example, on the Opel Astra, the USR valve is located under the engine protective cover in the right corner, and on the Opel Omega, on the right side of the ignition distributor. In any case, if you cannot find this element of the engine compartment, you should always first of all focus on the tube that is connected to the valve.

The only exceptions are turbocharged (or biturbin) engines. On such powerful engines, this system is simply not effective, and other safety measures are used to maintain a high environmental level. For example, a special device can be installed that cools the air entering the combustion chambers and thereby prevents the formation of nitrogen oxide.

What is the EGR valve made of?

The gases leaving the combustion chamber have a very high temperature. Therefore, this type of valve is made of high-strength steel, which is not afraid of high temperatures, and easily withstands heat of several thousand degrees Celsius. Directly, the design of the valve is quite simple (a classic exhaust valve capable of being in two open / closed positions). But the valve control system is very complex and works according to an intricate algorithm, which may depend on both the car model and the vehicle manufacturer.

The principle of operation of the EGR system.

It should be said that the principle of operation of this system is quite simple. The appearance of nitric oxide is due to the high temperature in the combustion chambers. Thus, if the temperature is reduced, then much less nitric oxide is formed, or it is not formed at all. Lowering the temperature in the combustion chambers is achieved as follows. The EGR valve opens and some of the exhaust gases are returned to the engine. Exhaust gases displace oxygen, the combustion rate in the chambers decreases, and then the temperature also decreases. As you might guess, such a system is very beneficial for the environment, but it significantly reduces the level of engine power.

Types of EGR system.

Currently, two types of USR systems are used: electronic, pneumatic and electro-pneumatic.

• Electronic EGR This type of system is managed, controlled directly by the on-board computer. The valve is opened by a stepper electric motor, and this affects its smooth opening in the most positive way. Typically there are 5-7 valve opening positions.
• Electropneumatic EGR In this case, several sensors can control the operation of the EGR at once. The choice of sensors depends on the class of the vehicle and its manufacturer.

The system can be controlled by:

• Exhaust pressure difference sensor
• Exhaust gas temperature sensor
• EGR valve sensor
• Mass air flow sensor An electro-pneumatic converter is responsible for the smooth opening of the valve, which is able to control the system very, very smoothly. A similar (very complex!) control system is usually used in premium cars.
• Pneumatic EGR The valve is operated by a spring, and is completely dependent on the throttle valve. The harder the driver presses the gas pedal, the more the valve opens. This EGR control method is the most inaccurate, and is usually used in low-cost, low-power vehicles.

Features of the use of the USR in Russia.

It must be said that the use of this system in Russia has a lot of specific features. Firstly, the quality of fuel in our country is at a rather low level. There is also enough frank counterfeit, which can run into at any (even the most prestigious) gas station. Poor quality fuel causes the EGR valve to become covered with soot and stop working correctly. All this negatively affects the operation of the engine. Secondly, many people (quite rightly) believe that the EGR system "chokes" the engine, and does not allow it to work at full capacity. Therefore, many service centers have a special function for deactivating the USR.

The main malfunctions of the USR system.

As mentioned above, the main problem of this design is low-quality fuel. Diesel engines are particularly affected. From low-quality fuel, soot can appear after 10-15 thousand kilometers.

In addition, the slightest malfunction of the engine (and combustion chambers), and contamination of the USR valve increases many times over. Leaking oil, compressor malfunctions, worn valve stem seals - all this reduces the life cycle of the EGR system.

• Soot on the valve. A layer of soot on the valve prevents it from opening and closing normally. Sooner or later the valve will stick. All this is characterized by unstable idling of the machine, uneven acceleration, and a general drop in engine power. Detonation can occur on gasoline engines, and loud pops and other unpleasant sounds will regularly occur. There are no single symptoms, since malfunctions depend on the design of the USR system.
• Burnt valve. This usually happens in the later stages of car operation (100-120 thousand mileage). The symptoms of a malfunction are exactly the same as with a jammed engine, since a warm valve is equivalent to a jammed one. However, such a repair will be more expensive, since the valve will need to be replaced. It should be noted that the vast majority of problems occur with the pneumatic EGR, since the spring-driven system cannot boast of high reliability. Minimal problems are delivered to their owners by an electronic system that is able to work with minimal maintenance for many years.
• Damage to other parts of the system. The valve is far from always to blame for the malfunction. Broken vacuum hoses, numerous electrical wires - all this can lead to a malfunction of the system as a whole. Therefore, all existing parts should be carefully checked before dismantling the valve.
• Control element failure. In rare cases, the on-board computer that controls the opening and closing of the valve may fail. Symptoms of a malfunction can be very different, since it is not known which parameters are not controlled correctly. In this case, the working firmware changes, and the on-board computer starts working correctly again. In most cases, the replacement of the device itself is not required.

Muffle or not muffle the EGR valve.

The service life of the USR system is 50-70 thousand kilometers. In the future, it is necessary to prevent or partially replace parts that have failed. Many car owners dismantle (jamming) the USR system, and get the following benefits:

• Increased engine power. Motor power is no longer dampened by the valve. This increases the total power by 5-7%, and ensures smooth acceleration in all engine operating ranges.
• No Faults Associated with the EGR Naturally, the disconnected and dismantled nitric oxide neutralization system no longer causes problems and does not require maintenance.
• Reduction of soot on pistons. Exhaust gases no longer flow back into the combustion chambers, and this reduces wear on the internal parts of the engine.
• Better fuel combustion The combustion chambers are kept at a consistently high temperature and the gasoline burns completely and completely, as originally intended.

Actually, there is only one drawback of dismantling the EGR system. The car no longer meets European emission safety standards.

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Today, all manufacturers are trying to make their cars as environmentally friendly as possible. Therefore, the EGR system was developed. There is a lot of debate about which engine is more environmentally friendly. In fact, how many people have so many opinions. Someone thinks cleaner than diesel, and someone vice versa. In order to clean the exhaust into the atmosphere, the EGR system was created.

Device

The EGR system is designed so that exhaust gases are cleaned by returning part of the gases back to the intake manifold. The return of exhaust gases is provided by the EGR valve. Since the engines do not differ in principle of operation, only the EGR valve actuator differs.

There are two ways to adjust the EGR valve.

• In the first case, the adjustment takes place using the controller of the internal combustion engine, which sends all instructions. In this case, the controller takes this data from the position sensor. This method is called electric.
• There is also a second method, it is called electropneumatic. In this method, the EGR system is based on the readings of the pressure and temperature sensors on the intake manifold, as well as the readings of the mass air flow sensor.

Advantages and disadvantages

The main disadvantage of the system is the rapid contamination of the intake manifold. This process is inevitable, so whoever has the USR still ends up with a contaminated intake manifold. There are several more disadvantages, the main of which is the rapid wear of the sensors and the USR valve. There is one more minus, which may not be, if you properly operate the car. This minus is considered soot, which is deposited on the USR valve and socket. So, this shortcoming can be bypassed.

In order for carbon deposits not to be deposited, it is required to refuel the car with high-quality fuel.

Nagar remains due to the fact that the cylinder-piston system wears out. A malfunction of the sensors that regulate the operation of the USR valve, malfunctions of the power supply system, turbocharger, crankcase ventilation - all this also leaves carbon deposits on the USR valve. If you properly monitor and take care of the engine in time, then this drawback may not be.

In addition to the disadvantages of the EGR system, there are a number of advantages. On a gasoline internal combustion engine, during the operation of the USR system, pressure surges in the mixing chamber are reduced during the opening and closing of the throttle. In a gasoline engine, the combustion temperature of the fuel is reduced, which reduces detonation. Reduced knock allows you to set the ignition earlier, which in turn improves the instantaneous performance of the engine. EGR on a diesel engine allows it to run quieter and smoother at idle. This happens because during the combustion of fuel in the system, the pressure decreases due to the fact that less oxygen is supplied.

Breakdowns

Often in the USR, as in other car systems, breakdowns occur, this is inevitable. Most often, breakdowns occur precisely because soot has appeared on the EGR valve or socket. This happens because the engine is running on low-quality fuel. The EGR valve can become carbonized due to improper operation of the turbocharger, pistons or cylinders, as well as incomplete combustion of fuel in the combustion chamber. If the sensors that contribute to the operation of the EGR do not work correctly or do not work at all, then this will also lead to disastrous consequences.

When the EGR valve is covered with soot, it stops working in the mode in which it worked before. There are situations when the valve is stuck. In any case, this should not be allowed. The fact that the valve does not work on time can be seen during idling. This will not lead to disastrous consequences for the internal combustion engine.

In the second case, when the valve is stuck, gasoline engines at idle will be unstable. On a gasoline engine, fuel consumption may increase in this situation. Diesel engines, in turn, will run harder and louder, and the engine will also noticeably reduce power.

In order to correctly determine the breakdown of the EGR, you will need to visually inspect all pipelines, as well as sensor connectors for dirt. In order to confirm the guesses, it will be necessary to carry out diagnostics, which will show the condition of the valve for the presence of soot, and also show the clogging of the collector.

If it was determined that the valve was covered with soot, then it should be changed. When replacing the EGR valve, you will need to clean all systems that work together. This must be done due to the fact that the remnants of soot can lead to the same breakdown again.

Silence

Many owners of cars with EGR believe that it "strangles" the engine and does not allow it to work at full capacity, and therefore come to the decision of how to turn it off. It should be noted that all engines are different, and the system is installed differently on them. There are two ways to disable the EGR.

1. The first way is programmatic muting. This procedure is not cheap. The cost of jamming the EGR costs approximately 9,000, and for some engines, even 14,000 rubles.

But do not despair, there is a second way to jam the system.

1. The mechanical way to stop the system, you just need to remove it. To drown out the second way, it will not take much effort and time, only a new gasket will be required. The new gasket does not have a second hole. Such a gasket can be purchased on the pages of online stores or made independently.

An important fact is that you should not make such a gasket from aluminum cans, because they will not withstand the temperature and will crumble into the system, which will not lead to good consequences.

The new gasket, unlike the factory gasket, does not have one hole. After the factory gasket has been removed, you need to put a new one and assemble the system back. It is not necessary to turn off the sensor that is installed on the valve so that the Check Engine does not light up later.

Summary

After reading the article, you can learn a lot about EGR, how to drown it out. All the advantages and disadvantages of this system, as well as ways to turn it off and break down, are described in detail. Each driver has his own opinion on the USR account, and only he can decide to turn off or leave this system.

The EGR valve is the main structural element of the exhaust gas recirculation system. The main task of the USR is to reduce the amount of nitrogen oxide formed per unit of burned fuel. The presence of the valve certainly has a positive effect on the operation of the engine, but subject to the high quality of the fuel and the complete technical serviceability of the car. Otherwise, the system starts to fail and malfunctions appear one after another. Since the EGR system is more environmentally friendly, shutting off the valve will not affect the dynamic performance of the car, so many car owners decide to take such an ambiguous step as interfering with Exhaust Gas Recirculation.

Purpose of EGR

Car exhaust contains many harmful substances, including nitrogen oxide and nitrogen dioxide. Their action on the human body leads to various diseases. The negative impact of NO and NO 2 is especially strong on residents of megacities, who are forced to stand in traffic jams for hours, so automakers strive to make their products as environmentally friendly as possible.

The ignition of the air-fuel mixture occurs at high temperature and pressure. Under such conditions, a chemical reaction of the combination of oxygen with nitrogen occurs. This phenomenon has a bad effect not only on the environment, but also on the power of the motor. The oxygen necessary for fuel combustion is not involved in the process, which worsens the ignition process. This leads not only to a decrease in power, but also to an increase in fuel consumption, since part of it does not burn out completely.

Exhaust Gas Recirculation allows you to add part of the exhaust gases to the intake manifold. There they are mixed with a fresh air stream. Since the proportion of oxygen in the exhaust gases is less, accordingly, a depleted O 2 mixture is supplied to the combustion chamber. In this case, ignition occurs at a lower temperature, which minimizes the formation of nitrogen oxides and dioxides. This technical solution has a good effect on both gasoline and diesel engines. In the first case, detonation decreases, and in the second, the rigidity of the motor operation decreases.

Valve principle

Exhaust gas recirculation does not have a single design solution. The first EGRs were implemented on mechanical control. Machines currently being produced are equipped with a controller that controls a valve. The control signals coming from the ECU are formed after processing the data received from various sensors according to the algorithms embedded in the ROM. The information most often needed for proper EGR operation is:

• EGR valve position;
• air temperature in the intake manifold;
• throttle opening angle;
• absolute pressure;
• coolant and engine temperature;
• air flow;
• the amount of oxygen in the exhaust gases;
• auxiliary data, depending on which sensor the automaker installed additionally.

Recirculation does not turn on when the engine warms up to 60°C. Also, the valve is in the closed position in gasoline engines at idle and under maximum load. In diesel engines, EGR works not only in motion, but also at idle.

Constructive decisions

Among the Exhaust Gas Recirculation, operating under the control of the ECU, there are two main types:

1. Electropneumatic. At the base is a pneumatic valve. They are widely used due to their simple design and higher reliability. The EGR contains pneumatic and solenoid valves. The first controls the exhaust gas passage, and the second affects the vacuum required for the system to work. The ECU sends a signal only to the solenoid valve, and it, in turn, controls the pneumatic valve, which is a spring-loaded membrane. When the vacuum above the membrane exceeds the action of the spring, the exhaust gas channel opens slightly;

   

2. Digital. Less common due to high cost and low reliability. At the base is an electronic signal. They have great handling, so they are installed on premium cars. In such systems, an EGR status sensor is often present.

   

   Regardless of the design, the entire system is very sensitive to fuel quality. Any deviation from the norm leads to valve damage. After that, the unstable operation of the motor begins, provoking the car owner to remove the USR.

   Valve cleaning

   Before you start cleaning the EGR, you need to determine where the valve is located. As a rule, it is located directly at the engine near the intake manifold. There is placement on the throttle valve block and in the suction tract. An example of where the valves are located in Chevrolet Lacetti cars is shown in the image below.

   

   Cleaning occurs by removing carbon deposits from the surface of the seat and stem. Instructions on how to clean the EGR system:

   1. Remove the terminal from the battery;
   2. Disconnect the cable from the valve;
   3. Unscrew the body mounting bolts;
   4. Put the insides soaked in liquid for cleaning carburetors;
   5. Clean the channel in the collector;
   6. Periodically repeat cleaning depending on the level of contamination;
   7. Lapping the valve with a special paste;
   8. Execute assembly;
   9. Before checking the efficiency of the EGR, it is required to check the tightness of the valve.

   Cleaning very often eliminates all problems with the USR. With their frequent repetition, it is necessary to remove the valve. Instead, a plug made of tin is placed.

   Silencing the EGR valve

   The malfunctions that have arisen with the valve can be solved radically, not by repair, but by plugging. It is only difficult to remove the UPK if the position of the diaphragm rod is measured during Exhaust Gas Recirculation. There are two ways to remove egr:

   1. Physically. It is required to cut a gasket from metal, similar in shape to a valve. Unlike the standard version, the plug should not have holes for the passage of gases;
   2. Programmatically. Despite the impossibility of exhaust entering the intake system, the ECU will signal recirculation. Receiving information about the incorrect operation of the EGR, the electronic control unit will report an error through the CHECK ENGINE ignition. It is possible to extinguish the light bulb only by reflashing the controller.

   The benefits that a car owner receives who decides to turn off egr:

   • there are no combustion products in the intake manifold that can clog it;
   • engine oil retains its properties for a longer period;
   • during maintenance, there is no need to clean and repair the EGR.

   A disabled recirculation system can bring the following negative consequences:

   • increased environmental pollution;
   • accelerated exit of the catalyst;
   • engine instability due to problems with the electronic control unit.

   You should choose a repair or a plug, focusing on the model of the car. In the absence of a malfunction in the operation of the valve, its removal is impractical. Moreover, if failures are constantly observed in the EGR, it is recommended to turn it off and forget about the problems.

   The installation of recirculation systems by car manufacturers is a necessary measure in the fight against pollution. Imperfect EGR leads to valve malfunction, which can often be corrected only by muffling it. A single answer on whether to delete the USR has not been found to this day.

   If you have any questions - leave them in the comments below the article. We or our visitors will be happy to answer them.

Translated from English - EGR means "exhaust gas recirculation". Part of the exhaust gases is returned to the cylinders for final combustion.

What is the egr valve for?

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Due to the action of the EGR from the exhaust manifold, part of the exhaust gases is returned to the intake manifold. Thanks to this function, exhaust toxicity is significantly reduced during engine warm-up, as well as during hard acceleration. In these two modes, the engine runs on an enriched fuel mixture.

The EGR system consists of several parts. The central part is the valve itself. Often, due to a violation of tightness, its malfunction occurs. In addition, being in constant contact with hot gases also does not contribute to much durability. The second part is the EGR solenoid. It is used in systems where the valve is controlled pneumatically.

The third element of the system is the EGR valve stem position sensor (aka the EGR valve opening degree sensor). It happens that he comes into a malfunction, but special troubles do not occur because of this. Unless the check engine light comes on. Finally, the last part is the engine control unit.

The principle of operation of the egr valve

The mechanism of operation of the system is based on the return of part of the exhaust gases to the intake manifold again. This process takes place over a certain period of time. Then the exhaust gases again enter the engine, but with a fresh mixture. All this is determined by the control unit in which a special program is installed.

The recirculation system functions only when the engine warms up to fifty or sixty degrees. After the engine picks up 1000 rpm or more, the recirculation system starts working and functions until an increase of 4000 rpm.

The EGR system does not function at high vehicle speeds and during acceleration, since at this time the engine is running at full power and it does not require a decrease in the concentration of nitrogen oxide in the exhaust gases. The recirculation system is used most actively when the car is moving at speeds from 50 to 120 km / h.

The recirculation system allows the motorist to save fuel consumption. This is achieved by depleting the combustible mixture: when the system is put into operation, a certain program is automatically launched. This process of functioning is controlled.

One of the tried and tested recommendations is to turn off the egr valve. In this case, the engine will work reliably and there will be no problems. In addition, it is desirable that the tachometer needle does not stay in the interval below two thousand revolutions for a long time. This will prevent the intake manifold from forming soot.

Malfunction of the EGR system

EGR valve from Toyota Rav 4

Valve leaks affect engine performance. In the general case, the normal process of combustion of the fuel mixture in the cylinders is disrupted. This happens due to a decrease in the amount of oxygen contained in the air that enters the engine. Other factors also play an important role in this case: the amount of exhaust gases entering the intake manifold, the general condition and engine speed.

In any engine control unit there is a program for stabilizing the speed. If this stabilization is successfully achieved, the increase in speed leads to an increase in pressure in the exhaust manifold. An increased amount of exhaust gases, which are little enriched with oxygen, begin to flow into the intake manifold. All this leads to instability of the engine itself.

Causes and symptoms of a malfunctioning egr valve

There are two main causes of failure:

• a small amount of exhaust gases passing through the valve of the recirculation system;
• too much exhaust gas passing through the system valve.

As a result of uneven settling of solid particles from the exhaust gases, the EGR valve begins to close loosely. In this case, it must be cleaned and installed in its original place, but before this it is necessary to free the channels from the effects of solid particles settling. If this is not done, the valve may become clogged again.

Restoring normal operation

Initially, the EGR system is designed for a car mileage of no more than eighty - one hundred thousand kilometers. After that, it is necessary to replace all components of the system. In domestic conditions, a complete replacement is optimal after 50,000 km. However, in practice, this is far from affordable for everyone. In this case, timely service can be advised.

The seat and stem must be thoroughly cleaned in order to subsequently ensure a tight seal and smooth operation. Sold in an aerosol, a special liquid used to clean the carburetor has an effective effect in this case. In this case, this liquid must not be allowed to enter the diaphragm.

If there is a solenoid, you need to clean the small filter in it. This device is designed to protect the vacuum system from dirt. After cleaning this filter, in many cases the malfunction disappears.

Often, after a valve failure, motorists try to drown it out. This is usually done with a spacer cut from thin sheet metal. There is no need to cut holes for the passage of gases. Only if the stem protrudes beyond the seating plane is it necessary to make a hole.

Thus, the EGR valve is of great importance during the normal operation of the recirculation system.