Malfunction of the EGR valve (USR). Signs, causes, repairs.

EGR valve or The EGR valve is one of the most important elements of your vehicle's anti-pollution system. This allows the exhaust gases to be recirculated in the engine to limit the amount of CO2 released from the exhaust gases. Mandatory equipment on all diesel engines, has a resource of 150 kilometers.

What is the EGR system and what is it for?

Exhaust gas recirculation, or EGR, is a special technology that helps reduce harmful emissions from vehicle exhaust. When fuel burns at high temperatures, nitrogen oxides (NOx) are formed, which are highly toxic substances. Once released into the atmosphere, they can contribute to the formation of smog and cause acid rain, which is harmful to both the environment and human health, causing respiratory problems.

Since the beginning of the 1990s, European countries have introduced environmental standards for cars, starting with Euro-1, which regulate the amount of harmful emissions. Over time, the requirements for cars have become increasingly strict. The EGR system includes an EGR valve and a cooler. The EGR valve returns some of the exhaust gases back to the engine cylinders through the intake manifold. This lowers the combustion temperature and reduces the amount of nitrogen oxides by up to 70%, without affecting engine power and even reducing fuel consumption. Many car owners prefer to turn off the EGR valve, believing that this component only causes harm and does not bring any benefit other than reducing emissions into the atmosphere. However, this statement is not entirely true. When the USR system is turned off, the following problems arise: 1. The risk of local engine overheating increases, which can damage its operation. 2. The engine warming up process slows down, which leads to increased wear. 3. Fuel consumption increases, which is especially noticeable when driving on the highway. In addition, vehicles without a USR system may not meet environmental standards for entry into some European cities and regions. For example, in Austria, Belgium, Germany, Denmark, France and the Czech Republic, there are environmental zones into which vehicles that do not meet Euro standards are prohibited from entering.

What are the causes of a faulty EGR valve?

Over time, the exhaust gas recirculation valve may start to show signs of fatigue and function less and less. This defect can be explained by several reasons:

• Deposit in the amount of calamine : this mixture of soot and impurities gets stuck in the exhaust gas recirculation valve, blocking its operation or even completely blocking it if present in large quantities.
• Un defective throttle body : This is what makes it possible to regulate the flow of air into the combustion chambers. Its malfunction can affect the operation of the exhaust gas recirculation valve.
• Leakage machine oil : most often it comes from the cylinder head, the gasket of which is not at all tight, and this leak will affect the serviceability of the EGR valve.

Thus, these three situations will cause the exhaust gas recirculation valve to fail, and failure will cause the following symptoms on your vehicle:

1. Engine warning lamp ignition : triggered when your car has too high a level of pollutant emissions;
2. Loss of engine power : during the acceleration phases, the engine struggles to reach high rpm.
3. Difficulty starting a car : when you turn on the ignition, you need to do it several times to start the engine;
4. Jerking while driving : since the engine is no longer running, it has a tendency to seize;
5. Exhaust smoke darkens : it will turn gray or even completely black depending on the level of carbon pollution;
6. Increased fuel consumption : The engine needs more fuel to operate.

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How does the EGR valve work?

Many car owners prefer to turn off the EGR valve, believing that this component only causes harm and does not bring any benefit other than reducing emissions into the atmosphere. However, this statement is not entirely true. When the USR system is turned off, the following problems arise: 1. The risk of local engine overheating increases, which can damage its operation. 2. The engine warming up process slows down, which leads to increased wear. 3. Fuel consumption increases, which is especially noticeable when driving on the highway. In addition, vehicles without a USR system may not meet environmental standards for entry into some European cities and regions. For example, in Austria, Belgium, Germany, Denmark, France and the Czech Republic, there are environmental zones into which vehicles that do not meet Euro standards are prohibited from entering.

Causes of EGR valve failure

The main cause of valve failure is the formation of carbon deposits in the channels and intake system. This deposit can lead to clogging of the tubes and passages through which exhaust gases pass, as well as clogging of the valve plunger mechanism. In some cases, the valve actuator may also break due to carbon deposits. These problems can cause the valve to become stuck open or closed, which can cause serious problems with the engine.

EGR valve symptoms

The following symptoms may indicate a faulty EGR valve:

1. The Check Engine light on the dashboard is on.
2. Reduced engine power and rough idle.
3. Increased fuel consumption as a malfunctioning EGR valve can alter the air/fuel mixture.
4. The appearance of detonation or knocking in the engine, which can be caused by improper functioning of the EGR valve and changes in combustion conditions in the cylinders.

If you suspect a faulty EGR valve, it is recommended that you contact a professional for diagnosis and repair.

What are the solutions for repairing the EGR valve?

To repair an exhaust gas recirculation valve if it is clogged, you can try 3 methods depending on the level of stored carbon:

• Cleaning while driving : it will be necessary to drive on an accelerated road, accelerating the engine to 3500 rpm for about twenty kilometers, in order to burn off all soot residues;
• Use of the additive : it is poured directly into your vehicle's fuel tank and is used to clean the entire engine system, in particular the particulate filter;
• Un descaling : This solution is the most effective and must be carried out by a professional who can remove all the carbon present in the engine system and exhaust circuit.

How to replace the EGR valve?

If your exhaust gas recirculation (EGR) valve has completely failed, no amount of cleaning will fix it and it will need to be replaced as soon as possible. Follow our step-by-step instructions to succeed in this operation yourself.

Required material:

• Toolbox
• Protective gloves
• Diagnostic case
• New EGR valve

Step 1: disconnect the battery

To ensure safe operation, the negative pole of the battery must be disconnected. It is black, symbolized by the sign -.

Step 2. Disassemble the exhaust gas recirculation valve.

Start by disconnecting the vacuum pipe, then remove the screws holding the EGR valve. Repeat the operation with the screws of its pipe and exhaust manifold. Then it will be necessary to remove the diffuser from the exhaust gas recirculation valve, as well as the gasket from the exhaust manifold pipe. You can now remove the faulty exhaust gas recirculation valve.

Step 3: Install a new EGR valve.

You can now install a new EGR valve and reconnect your vehicle's battery. It is highly recommended that you reconfigure your computer using the diagnostic kit and its software.

What to do if the EGR valve actuator is broken?

EGR valve malfunction is often associated with a broken gear in its drive. There are several ways to solve this problem: 1. The first option is to purchase and install a new unit. This option provides a guarantee, but its disadvantage is the high price. For some car models, a new EGR valve can cost more than 500 EURO, and this does not include the cost of work at a car service center. 2. The second option is to purchase a contract or used unit. A contract unit costs less than a new one, starting from 70 EURO on the secondary market. However, such spare parts are not provided with a warranty, and there is a risk of receiving a faulty or low-quality unit. 3. The third option that the service station may offer is to turn off the recirculation valve. However, this option carries the risk of overheating the engine and increasing wear due to improper operation of the system. 4. Another option is to restore the drive using a repair kit. This option has many advantages, including a more affordable price. The cost of a repair kit for the recirculation valve is 10-15 EURO. The repair kit includes a new wear-resistant gear, silicone grease to protect parts from wear, as well as detailed installation instructions with photographs. This repair kit is suitable for VAG family vehicles such as Audi, Volkswagen, Skoda and Seat. Installing a repair kit allows the EGR valve to restore functionality like a new car from the factory.

What are other possible symptoms of a bad EGR valve?

If your EGR valve is malfunctioning but you didn't notice it, it could cause significant damage to your particulate filter and intake manifold. Moreover, if the coal is properly installed in the intake system, it is turbocharger which could be seriously damaged by it.

The exhaust gas recirculation (EGR) valve is a mechanical part that is part of the process to reduce pollutant gas emissions. Therefore, its correct functioning is a prerequisite for legal driving and passing your technical control. At the slightest sign of wear and tear, book an appointment at a trusted garage using our online comparator!