Bad EGR Valve Symptoms


Exhaust Gas Recirculation (EGR) valves play an essential role in a car’s emissions system. They regulate the amount of exhaust gas that goes back into the engine to be burned instead of being released out. When an EGR valve fails, it can cause problems that manifest in different ways.

Here are some common bad EGR valve symptoms:

  1. The check engine light is on.
  2. There’s a rough idle or hesitation when accelerating.
  3. Poor fuel economy.
  4. Black smoke is coming from the exhaust pipe.
  5. The engine runs hot, especially when idling.
  6. The vehicle fails emissions tests.
  7. There’s a rotten egg odor coming from the exhaust.
  8. The vehicle is stalling or misfiring.
  9. There’s a lack of power when climbing hills.
  10. Decreased engine performance.
  11. Irregular engine noises.

Read on for a rundown of these common problems and what you can do about them if your EGR valve isn’t working correctly.

1. The Check Engine Light Is On

The check engine light is one of the most common indicators that something may be wrong with your EGR valve. When this light appears on your dashboard, it can signal several problems, from a faulty sensor to an issue with the valve itself.

If your check engine light comes on, the first thing you should do is take your car to a mechanic for a professional diagnosis. The mechanic will be able to get you the information you need about what’s going on with your EGR valve and give you steps for getting it repaired or replaced as required.

In the meantime, it’s important to drive carefully, as any issues with your EGR system could affect how well your car functions overall.

Read: What Does The Service Engine Soon Light In My Car Mean?

2. There’s a Rough Idle or Hesitation When Accelerating

If your EGR valve is faulty, you may notice that the engine runs rough while idling and tends to hesitate when accelerating. This is caused by the increased amount of exhaust gas that isn’t adequately burned inside the combustion chamber.

When you experience idling, it’s best to take your car to a mechanic as soon as possible. They can help you troubleshoot the problem and get your EGR valve replaced if necessary.

Read: Why Is There White Smoke Coming From The Engine?

3. Poor Fuel Economy

Another common problem caused by a bad EGR valve is decreased fuel economy. This happens because the engine isn’t running as efficiently as it should be, and is using more fuel than necessary to make up for the lost power.

Specifically, when the EGR valve fails, it can cause the engine to run lean. This means that there’s too much air and not enough fuel, leading to decreased performance and fuel economy.

If you’ve noticed that your car isn’t getting the gas mileage it used to, it’s good to have the EGR valve checked out by a professional. They can tell you whether or not it’s the root of the problem.

4. Black Smoke Is Coming From the Exhaust Pipe

Exhaust that’s darker than normal or has a black tint can also signify a bad EGR valve. This happens because the increased amount of exhaust gas going back into the engine isn’t being burned off properly. When this happens, the unburned gas can mix with the oil and cause it to burn. This will create a black smoke that comes out of the exhaust pipe when the engine is running.

If you notice black smoke coming from the exhaust pipe, take your car in for service. The sooner you get the EGR valve fixed, the better.

Read: 5 Reasons Why A Car Engine Knocks On Startup Then Goes Away

5. The Engine Runs Hot, Especially When Idling

If your engine is running hotter than normal, it could signify that the EGR valve isn’t working properly. When the valve fails, it can cause the engine to run lean, as I mentioned before. This can lead to increased temperatures, both when the engine is idling and running at higher speeds.

Therefore, if you’ve noticed that your car has been running hotter than usual, make an appointment with a mechanic as soon as possible. They’ll be able to help you diagnose the problem and come up with solutions for getting it fixed or replaced.

6. The Vehicle Fails Emissions Tests

When your EGR valve isn’t working properly, it can cause your car to fail its smog test.

These tests measure a vehicle’s impact on air quality and fuel efficiency. When the EGR system isn’t operating correctly, it can increase engine emissions, such as carbon monoxide or nitrogen oxides. This could result in higher levels of environmental pollution, resulting in failed emission tests.

Read: When Should You Replace The Engine Air Filter?

7. There’s a Rotten Egg Odor Coming From the Exhaust

If you notice a strong, unpleasant odor coming from your car’s exhaust pipe, there’s likely a problem with your EGR valve.

As I previously mentioned, the EGR valve regulates the flow of exhaust gases to reduce engine emissions and increase fuel efficiency. When this valve is not functioning correctly, it can result in a buildup of noxious gases that can cause a foul smell to come from the exhaust.

While there are other potential culprits behind the foul-smelling gases, such as a leaking muffler or excessive oil buildup in the combustion chamber, the most likely cause is an issue with your EGR valve.

It’s best to take your car in for diagnostic testing as soon as possible to address any issues and get back on the road without having to deal with unpleasant odors.

8. The Vehicle Is Stalling or Misfiring

If your vehicle stalls or misfires frequently, it could signify that the EGR system isn’t functioning properly. When the EGR valve gets stuck in the open position, it can cause an imbalance of air and fuel in the engine. This can lead to stalling or misfiring.

So, if you notice that your vehicle is misfiring or stalling frequently, get the EGR valve checked out by a mechanic right away. They’ll be able to give you more information on how to address any problems you may be experiencing and get your car up and running in no time.

9. There’s a Lack of Power When Climbing Hills

Another typical symptom of a faulty EGR valve is a lack of power when climbing hills. This is because the valve cannot properly regulate the flow of gases, which leads to an imbalance in the air-to-fuel ratio.

As a result, the engine doesn’t have enough power to overcome the resistance of the hill. If you notice this problem, it’s important to have the EGR valve checked as soon as possible. A qualified mechanic will be able to test the valve and make any necessary repairs.

10. Decreased Engine Performance

If you notice a decrease in your engine’s performance, it could signify a problem with the EGR valve. The EGR valve can become clogged with carbon deposits, resulting in a loss of horsepower and reduced fuel mileage.

Still, there are several other potential causes for decreased engine performance, including a dirty fuel injector or low oil levels. To know for sure what is causing your vehicle’s problems, it’s best to get an expert opinion from a mechanic.

Read: What Happens If The Car Engine Coolant Is Low?

11. Irregular Engine Noises

Finally, if you start to hear strange or irregular noises coming from your engine, it could be a sign of an issue with your EGR valve.

Some of the noises that may indicate a problem include knocking, rattling, grinding, or chattering. These noises are often caused by deposits of carbon buildup in the valve and can be alleviated by having the EGR valve cleaned.

What To Do if You Have a Bad EGR Valve?

If you have a bad EGR valve, the best thing to do is take your car in for service as soon as possible. A qualified mechanic will be able to diagnose the problem and come up with solutions for getting it fixed or replaced.

Besides taking your car in for service, you can do a few things to help address the problem in the meantime. For example, if you have a clogged valve, you can try using an EGR cleaner to clean it out.

Here’s a YouTube video on how to clean an EGR valve using an EGR cleaner:

However, if the problem is severe, you may need to have the valve replaced. This is something that a qualified mechanic should do.

Tips for Maintaining Your EGR Valve

Now that you know more about the symptoms of a bad EGR valve, and what to do if you have one, here are some tips for keeping your EGR valve in good working condition:

  • Inspect the EGR valve regularly for any signs of damage or corrosion.
  • Clean the EGR valve regularly to prevent carbon buildup.
  • If the EGR valve is not functioning properly, get it replaced as soon as possible.
  • Unless you have previous experience working on these valves, avoid making any modifications to the EGR valve yourself, as this can cause serious damage to your engine.

Pro Tip: To keep your car in the best shape, ensure you follow a strict maintenance schedule. You can use this Elegant Simple Trackers Log Book from It comes with up to 110 pages you can use to record all services and repairs done to your car, making it easy to keep track of needed maintenance.

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