Blog Car Care Advice 8 Typical Symptoms of a Bad EGR Valve to Look Out For
Car Care Advice

8 Typical Symptoms of a Bad EGR Valve to Look Out For

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The EGR valve is an often overlooked component in your vehicle’s Exhaust Gas Recirculation or EGR system. However, if it malfunctions, it can lead to engine performance issues and increased emissions.

What are the indicators of a bad EGR valve?
And how can you diagnose it?

Continue reading to find out!

This Article Contains

Let’s get to it.

8 Typical Bad EGR Valve Symptoms

The EGR valve redirects exhaust emissions into the combustion chambers to reduce your car’s nitrogen oxide (NOx) emission. 

When the exhaust gas recirculation valve fails, there are two ways it can happen:

But how can you know if it’s stuck open or closed?
Here are eight symptoms of a faulty EGR valve:

1. Rough Engine Idle

The first sign of a failing EGR valve is when your vehicle undergoes a rough engine idle, either when starting the engine or during brief stops. This happens when the EGR valve stays stuck open, causing the exhaust gas to flow continuously into the exhaust manifold. The overflow of exhaust gasses causes an incorrect air fuel mixture inside the combustion chamber.

2. Engine Knocking or Pinging Sounds

When the EGR valve is stuck closed, the temperature inside the combustion chamber will continue rising and overshooting the threshold for proper combustion temperature. This can cause the fuel to ignite earlier than it should, especially at low RPMs. The untimely fuel combustion may cause engine knocking. If you ignore this symptom, you may risk ruining the other components of your vehicle, like the spark plugs.

3. Smell of Fuel

When the valve isn’t working as it should, your engine will most likely burn more fuel than it’s supposed to. This causes your engine to release more unburnt hydrocarbons in the exhaust emissions, and you’ll be able to smell fuel in the back of the cabin. You’ll also notice decreased fuel efficiency. 

4. Increased Fuel Consumption

The exhaust gas recirculation valve opens and closes based on the throttle movement and exhaust manifold vacuum. When carbon deposit builds up in the valve, the EGR valve gets stuck open. This allows exhaust gas to reenter the combustion chamber in an untimely manner. It also results in a vacuum leak, adversely affecting your fuel economy as the engine tries to compensate by increasing fuel consumption.

5. Increased Emissions

A functional exhaust gas recirculation valve helps to reduce the amount of NOx emissions from your car’s exhaust fumes. However, a faulty valve can cause the exact opposite of it.

This can happen in two ways:

6. Reduced Engine Performance

Driving with a faulty EGR valve can cause reduced engine performance, especially when accelerating. This happens because your engine is running with an incorrect air fuel mixture.

Consequently, your engine’s fuel efficiency drops as it uses more fuel to achieve the same power output, and your car takes longer to reach higher speeds. Driving in this state can cause the engine to suddenly shut off while you’re on the road.

7. Overheating

A malfunctioning EGR valve can contribute to engine overheating, especially when stuck closed. 

When the EGR valve is stuck, it can’t redirect the exhaust gasses back into the combustion chamber to burn along with the fresh fuel mixture. As a result, the oxygen concentration inside the chamber increases, and the engine burns more fuel. Thus increasing the engine temperature.

8. Illuminated Check Engine Light

A faulty EGR valve can trigger the Check Engine light if it prevents the Mass Airflow (MAF) and Evaporative Emission Control (EVAP) sensors from identifying the volume of air needed for combustion. This is more prominent in vehicles with digital EGR valves since the Engine Control Unit (ECU) directly controls the movement of the valve.

If the Check Engine warning light comes with the other symptoms mentioned, you might have a failing EGR valve. However, these symptoms can also be caused by other faulty components. 

So, how does a mechanic conclude that a bad EGR valve is the cause of all those troubles?

How to Test and Fix a Bad EGR Valve

Here’s how a mechanic would diagnose and replace a faulty EGR valve:

  1. They’ll connect an OBD II scan tool to the engine and look for any EGR valve-related trouble codes.
  1. If there is one, they’ll remove the EGR valve and manually inspect it for physical signs of wear, clogging, and carbon deposit buildup.
  1. They’ll clean up the valve using an EGR system cleaner and a brush to remove debris.
  1. Once cleaned, they’ll look for signs of damage and aging or test the valve to see whether it works as it should. For vacuum-operated valves, the mechanic would test them using a handheld vacuum pump. For digital EGR valves, they’ll use a multimeter and test to see if current flows through it.
  1. If the valve is faulty, they’ll install a replacement.
  1. Finally, they’ll test the functions of the components (EGR valve, valve gasket, etc.) and take your car for a test drive to check for any issues.

Now you know how a mechanic diagnoses and replaces a malfunctioning EGR valve. Let’s review a few FAQs.

4 FAQs about the EGR Valve

Here are the answers to some common doubts about the exhaust gas recirculation valve to help you understand the component better.

1. Can I Drive With a Faulty EGR Valve?

Yes, you could drive with a bad EGR valve, but it’s not recommended. Driving your car to the nearest repair shop is safe, but driving for extended periods with a malfunctioning EGR valve can further damage your engine.

2. What Causes EGR Valve Failure?

There are various reasons why an EGR valve can fail, including:

3. How Often Should You Replace the EGR Valve?

The typical EGR valve can last about 10 years with routine maintenance and checks. 

However, it’s best to refer to your owner’s manual for specific replacement intervals for your car model. You could also consider replacing it when there’s physical damage or an identified EGR valve problem. 

4. How Much Does an EGR Valve Replacement Cost?

You can expect to pay between $200 and $1,250 for an EGR valve replacement. The actual EGR valve replacement cost depends on your vehicle’s complexity, labor charges in your area, and the part cost. 

Final Thoughts

Your vehicle’s exhaust gas recirculation valve plays a vital role in the exhaust system, primarily optimizing engine performance. Plus, identifying bad EGR valve symptoms early on can help you address the EGR problem sooner and avoid costly repairs. So, if you suspect a faulty EGR, you should immediately seek professional help. Better yet, let the professionals come to you with AutoNation Mobile Service!

AutoNation Mobile Service is a mobile auto repair service available seven days a week. We offer a 12-month | 12,000-mile warranty on all repairs.

Contact us today to get your EGR valve problem looked at, and we’ll send our expert technicians to your driveway ASAP.