Updated at: 03-08-2022 - By: Lucas

What is Exhaust Gas Recirculation or EGR?

As a part of a car’s EGR system, exhaust gases are circulated into the intake to lower the combustion temperature, reducing emissions. NOx emissions are reduced as a result of this method.

Electro-pneumatically operated EGR valves were the first to be manufactured. The electronic part of the EGR was protected from overheating because to this drive design. In today’s modern engines, the electronic engine control unit (ECU) is in charge of nearly all of the engine’s electrically driven valves.

With a DC electric motor instead of an electro pneumatic drive, EGR valves can respond more quickly. The opening and closing of these valves can be accomplished in less than 100 milliseconds. As a result, the EGR valve is fully closed when the driver desires the most torque.

How does the EGR valve work?

Exhaust Gas Recirculation Cooling Valve-2

EGR is a mechanism that permits combustion gases to be reintroduced into the intake manifold after being removed. Because it eliminates the two ingredients that underpin the formation of NOx, this technique results in a significant reduction in emissions.

Flue gas can be reintroduced into the intake to replace some of the oxygen needed for combustion, resulting in a reduction in surplus oxygen. Flue gas absorbs portion of the heat created by the combustion, reducing the maximum temperature each cycle.

The EGR valve is controlled by a computer that runs a solenoid in sequential masses. Vacuum pump pressure works on the EGR valve and opens it if the injection computer has a strong grip on the valve.

Carbon and calamine particles accumulate in the intake due to the exhaust gas recirculation operation. Carbon and calamine particles stick to engine components if action is not taken quickly enough. This reduces the engine’s ability to operate at its best.

As a result, replacing the EGR valve is a need. Engine decarbonization is a common option in the automotive industry, but I don’t like it because I haven’t seen any results, and I’ll explain why in a subsequent essay.. Decarbonization should be considered prior to switching to an EGR valve, as it appears that you will need to take your vehicle to a shop for an inspection and replacement.

Can petrol engines have EGR?

There is no need for an EGR system in most petrol engines because they use a stoichiometric mixture. Engines with direct injection and stratified mixing may need the usage of the exhaust gas radiator (EGR) as an exception to this rule.

How can an EGR valve get stuck?

Open or closed, it can be permanently locked in either position. Neither of these options is a good idea, but here are the repercussions if you do.

What problems can a stuck EGR valve cause to the car?

Is it open? If so, you need to close it.

  • The engine becomes saturated in a very short time.
  • The acceleration power will drop dramatically, and the engine may stop at idle or while driving.
  • Turbocharger problems. If the EGR remains open and the exhaust gases do not cool, the result is as clear as possible, namely that the exhaust gases will not cool. Once the engine overheats, the engine oil breaks down and takes the turbocharger path, and for this reason, the turbocharger suffers, failing to function.
  • Engine problems. If too much overheating of the engine is reached, the lubrication will be consumed permanently, which means that the engine instead of consuming fuel, will consume its own oil, which is why the engine will disintegrate, and in this situation, a new engine will be needed

If it’s stuck closed, here’s what you should do:

  • The valve will no longer have the power to operate. It’s as if you were canceling an engine component.
  • Nitrogen oxide emissions will exceed the limit allowed by law – this will be observed with the naked eye as the smoke becomes darker and denser.
  • Another symptom of the car that I noticed is that the engine is louder.

What can I do if the EGR valve is stuck?

As I previously stated, you should take your vehicle to a mechanic for a diagnosis, and if necessary, have the EGR replaced or cleaned; this is the simplest option. The price of the EGR valve varies depending on the model and the brand.

Correct diagnosis of EGR problems

Exhaust Gas Recirculation Cooling Valve

The injection computer monitors the EGR, which is a mechanism for lowering nitrogen oxide emissions, in order to detect probable problems. The Check Engine light will illuminate if an EGR issue is identified, as it is a pollution control system.

EGR Valve diagnosis

The torque of the engine and the amount of pollution it emits are both influenced by the location of the EGR valve. The majority of EGR valves come with a position sensor built in, which sends data to the injection computer when the valve is open or closed.

EGR valves can become clogged, as previously stated, as a result of particle accumulation. Locking an EGR valve might affect the engine’s integrity or pollutant emissions, depending on the location. Because of this, if the EGR valve is blocked in the closed position, the flue gas will no longer enter the intake manifold, and the nitrogen oxide emissions will go up.

Flue gases are recirculated all the time in the inlet of the engine if the EGR valve is blocked in the open position, which can damage the engine’s safe operation due to the high temperature.

OBD error codes for a faulty EGR valve

  • P0400 – Exhaust Gas Recirculation Flow Malfunction
  • P0401 – Exhaust Gas Recirculation Insufficient Flow
  • P0402 – Exhaust Gas Recirculation Excessive Flow
  • P0403 – EGR Control Circuit
  • P0404 – EGR Control Circuit – signal outside limits
  • P0405 – EGR Sensor “A” Circuit – signal below the minimum limit
  • P0406 – EGR Sensor “A” Circuit – signal above the minimum limit
  • P0407 – EGR Sensor “B” Circuit – signal below the minimum limit
  • P0408 – EGR Sensor “B” Circuit – signal above the minimum limit
  • P0405 – EGR Sensor “A” Circuit
  • P0486 – EGR Sensor “B” Circuit
  • P0489 – EGR Sensor “A” Control Circuit – signal below the minimum limit
  • P0490 – EGR Sensor “B” Control Circuit – signal below the minimum limit
  • P2413 – Performance of exhaust gas recirculation system – below the limit

Exhaust Gas Recirculation Cooling Valve diagnosis

EGR systems are employed in part to lower the cylinder’s combustion temperature. No considerable reduction in nitrogen oxide emissions may be achieved by directly introducing flue gases into the exhaust manifold.

EGR cooled systems have been standard equipment on nearly all diesel-powered automobiles since 2001. Exhaust gases are cooled in a radiator circuit before entering the engine in these systems. It is common practice to utilize engine coolant as a means of cooling exhaust gas.

The density of the gas and the EGR system’s efficiency are both boosted as a result of cooling.

  • the combustion temperature in the cylinder decreases
  • the amount of oxygen in the fresh gas decreases due to the higher density of the flue gas

After the engine temperature exceeds a particular threshold, the flue gas cooling is turned off. Allowing flue gas to either travel through or bypass a radiator is made possible by a by-pass valve in the cooling system.

OBD error codes for the EGR cooling Valve

  • P2425 – Exhaust Gas Recirculation Cooling Valve Control Circuit / Open
  • P2426 – Exhaust Gas Recirculation Cooling Valve Control Circuit – signal below the minimum limit
  • P2427 – Exhaust Gas Recirculation Cooling Valve Control Circuit – signal above the minimum limit
  • P2457  Exhaust Gas Recirculation Cooling System LOW Performance
  • P245A Exhaust Gas Recirculation Cooler Bypass Control Circuit / Open
  • P245B Exhaust Gas Recirculation Cooler Bypass Control Circuit Range / Performance – signal outside limits
  • P245C Exhaust Gas Recirculation Cooler Bypass Control Circuit Low
  • P245D Exhaust Gas Recirculation Cooler Bypass Control Circuit High

Temperature sensor

The injection computer makes the choice to cool the flue gas depending on the temperature sensor’s readings. It measures the temperature of exhaust gas before it enters the intake manifold.

EGR temperature sensor OBD error codes

  • P040A EGR Temp Sensor Circuit
  • P040B EGR Temp Sensor Circuit Range – signal outside limits
  • P040C EGR Temp Sensor A Circuit Low
  • P040D EGR Temp Sensor A Circuit High
  • P040E EGR Temp Sensor Circuit Intermittent
  • P040F EGR Temperature Sensor discrepancy between ‘A’ and ‘B’ sensor signals
  • P041A EGR Temp Sensor B Circuit
  • P041B EGR Temp Sensor B Circuit signal outside the range
  • P041C EGR Temp Sensor B Circuit Low
  • P041D EGR Temp Sensor B Circuit High
  • P041E EGR Temp Sensor B Intermittent Circuit


Only the EGR valve or the throttle in the intake manifold can be used to regulate the flow of exhaust gas. The shutter looks like a throttle on a car, but it has a very different function.

The intake manifold’s flue gas flow can be increased by closing the throttle, which reduces the amount of fresh air entering the engine and increases the amount of exhaust leaving the engine.

OBD codes for the throttle

  • P0487 EGR Throttle Control Circuit A Open
  • P0488 EGR Throttle Position Control Range / Performance
  • P213A EGR Throttle Control Circuit B Open
  • P213B EGR Throttle Position Control Circuit B Range / Performance
  • P213C EGR Throttle Position Control Circuit B Low
  • P213D EGR Throttle Position Control Circuit B High
  • P2141 EGR Throttle Position Control Circuit A Low
  • P2142 EGR Throttle Position Control Circuit A Low

How to clean an EGR valve?

Many EGR valves have been broken and repaired to work again, however buying a brand new one is usually less expensive than repairing an old one.

Due to their vacuum-controlled nature, older EGR valves are more easier to fix than their newer counterparts. Vacuum-controlled EGR valves can only have their inner membranes replaced or cleaned so that they function like new EGR valves.

EGR valves in newer vehicles feature a variety of electrical components, making them tough to fix even for the most experienced mechanics.

As a result, new EGR valves are the best choice in this situation.

Also newer generation cars have electric motors and EGR, but the arc valve is still in use. These can be damaged if they get trapped and the shaft is cleaned and lubricated, which can ruin them.

EGR valve cleaning begins with removing the curve with a knife, followed by multiple cleanings with a special brake cleaner.

Once you’ve completed this step, you’ll need to lubricate the valve with WD-40 to ensure that the pieces move as they should.

If changing the EGR valve appears more convenient, keep in mind that if your car’s EGR valve is electronic, you’ll need to utilize an OBD2 scanner to clear any trouble codes that may have been left behind after the change.

It is also required to use this scanner to configure the new EGR valve’s fundamental settings. EGR valves can be replaced, but if they don’t fit properly, the car will most likely need to be taken in for servicing.

Once you’ve determined that the EGR valve is malfunctioning, you should have it repaired immediately so that you can leave the problem in the hands of the professionals.

For those who don’t like the notion of having this component replaced, here are some actions you may take: First, clean the EGR valve, then remove the jams and check the valve working mode.

  • Therefore, it is necessary to disconnect the car battery, after which you must disconnect the sensors and the clamps, and then you must loosen the screws that hold the EGR valve.
  • Once you have completed all these steps, you will need to use a specially designed EGR device to clean the hoses and valves.
  • After you finish cleaning the hoses and valves, you will need to reconnect the car battery. It is extremely important that you do not allow the special cleaning agent to reach one of the electrical components of the machine.
  • However, to clean certain electrical components, it would be advisable to use a special electrical device created for this purpose.
  • If you have not yet gone through such a process with your personal car, our recommendation is to take your car in service for the specialists to deal with this aspect.
  • Depending on the car service chosen, but also depending on the make and model of the car, and not least on the basis of its age, you will be able to pay more or less for this intervention.

How to detect a failing EGR valve?

As previously mentioned, the EGR valve type that a vehicle possesses has a significant impact on how to detect a malfunctioning EGR valve. You can resolve the issue on your own if you follow the procedures outlined in this article.

  • If you want to test an electronic EGR valve for a vacuum controlled EGR, first of all, you need to check the vacuum hose between the inlet and the EGR.
  • You need to have a vacuum pump handy to use in order to open the EGR valve and to see if the pressure is maintained.
  • If it is not under pressure, it is necessary to change the membrane if you have this possibility, or if not, to change the whole EGR unit.
  • It is also necessary to remove the EGR valve and find out if it opens when you operate the vacuum pump. If the EGR valve behaves normally, it is necessary to check the solenoid, whose role is to control the EGR valve, and also here it is necessary to check the power and the presence of the grounding.

EGR controlled electronic system

  • First of all, you need to remove the EGR valve unit to see what the valve opening and closing is. Then, you need to connect a car battery charger when you are diagnosing, to find out if the voltage in the car is good when the diagnosis occurs.
  • The next step is to open and close the EGR valve using the OBD2 scanner. This procedure must be performed several times to verify the function.
  • Then, it is necessary to make a basic setting and to reset the saved parameter, with the scanner. It is also necessary to check all the problems regarding the EGR wiring.
  • After that, you must open the EGR valve and see if there is water inside the valve, or if there is corrosion infiltration, and you must use an electrical cleaning device to clean the EGR valve if you find that there is corrosion.
  • Then reinstall the EGR valve and try again this entire process, but if the EGR valve is defective, then you need to replace it with a new one.

How much does an EGR cost?

If you’re replacing an EGR valve, expect to pay anywhere from $55 to $300 for the part, with labor costs ranging from $20 to $60.

Older cars are equipped with vacuum controlled EGR valves, so drivers who own such cars can feel lucky because if necessary, they will spend less money.

Newer cars, however, have an EGR cooler integrated with the EGR valve, so you can not just replace the EGR valve but also the EGR cooler, and the Volkswagen cars are an example in this case.

If, for example, an old car needs a new EGR valve, the price for it may be less than $ 90. For newer cars, however, the prices are higher.

featured image by Towel401, distributed under a CC BY 2. 0 license.