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Faulty EGR Valve Symptoms on a Diesel Engine

Posted by on May 11, 2018 | 0 Comments

faulty diesel egr valve

Mostly all the diesel-powered vehicles on the road now have an EGR system (Exhaust Gas Recirculation).

The EGR makes use of an EGR valve which often wears out due to lack of maintenance and results in a poor performance. In this article, we will discuss the symptoms you might notice if the EGR valve is damaged and how to take care of the situation.


What is an EGR Valve?

Exhaust Gas Recirculation sounds like a self-explanatory term but its application is a little complicated yet sophisticated. The EGR system recirculates the exhaust gasses back into the inlet manifold and uses them for combustion.

This process not only reduces the harmful emissions of NOx but also helps the car to stay within the legal pollution limit. As the exhaust gas is recirculated, the combustion temperature reduces, preventing the production of NOx.

There are some disadvantages of EGR as well such as loss in fuel economy, low performance and in diesel-engine cars, the production of soot increases.

However, modern engines use clever technologies for an efficient process, for example, new diesel engines now use EGR cooler which cools down the exhaust gasses by passing the coolant.


Common Problems Associated with EGR Valve

Since the EGR deals with exhaust gasses such as carbon dioxide and NOx, it has a good chance of getting damaged or clogged over the years. This in turn, reduces the car’s performance and increases pollution as well. When there is a problem with the EGR Valve, the check engine light or EPC(VW) light may occur on your dashboard

The two main issues EGR valves face are that, either the valve stays open or it shuts completely.
Here are some common symptoms you will notice if you have a bad EGR valve.


Poor/Rough Idling

This happens when the engine is at a low RPM and the EGR valve remains open allowing additional gasses ultimately resulting in the performance drop of the engine.

Black Smoke from Exhaust

If the EGR valve stays open at all times and the exhaust fumes are being fed to the engine constantly, the engine gets deprived of oxygen. With too much fuel burning and less oxygen, a black smoke gets produced and escapes from the exhaust pipe especially when the car is idle.

Check Engine Light Illuminates

If the car’s on-board computer detects any problem with the vehicle’s EGR valve circuit, it will activate the check engine light. Please note that the check engine light can also be activated due to numerous other reasons. You can read the computer at home with an OBD2 code scanner

Drop in Fuel Economy

With the incorrect fuel/air supply, the engine will not function properly and this will result in the drop in fuel economy.

Engine Stalling

If you notice that the engine is stalling at higher revs, it is possibly due to a bad EGR valve. This can also result in the engine getting choked.

Turbocharger can Fail

If the EGR Valve & Cooler remains closed and the exhaust gasses are not cooled down, the engine’s temperature will rise significantly. As the engine overheats, it breaks down the motor oil which is heading towards the turbocharger causing the turbocharger to fail.

Engine Disintegrates

If the engine overheats too much, it will consume all the lubrication and will even start using its own engine oil instead of the diesel fuel. This will cause the engine to disintegrate.


Repairing a Broken EGR Valve

Now that you have concluded that the EGR Valve is faulty, it is time to repair it. You can either take it to the official dealership or try these methods to save some money.

Mostly, the EGR valve gets dirty and clogged as it recirculates the gasses continuously. Follow these steps to clean the valve and remove blockage and notice if it functions properly.


  • Disconnect the battery
  • Disconnect sensors and clips
  • Loosen the bolts holding EGR valve
  • Clean the valves and hoses with an EGR or Carburetor cleaner. You can find one on Amazon here: Genuine EGR System Cleaner – 1 Liter
  • Connect the battery again


Make sure to not spray the cleaner on any other electrical component. Instead, buy an electrical which will help you clean those certain components. For newbies, we recommend that you take your car to an auto-specialist who can diagnose the problem effectively and provide you with a solution.


On average, the EGR valve replacement should cost somewhere between $200 to $900. The component itself costs around $70 to $490. It’s often the repair time that is expensive.

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