Can a Bad EGR Valve Cause the Engine to Misfire?

One day I was driving my car to the store when suddenly, the car engine started misfiring. I pulled over to the side of the road, turned off the engine, and got my car towed to a qualified mechanic. After the mechanic checked out my car, he told me that there was a problem with my vehicle’s EGR valve.

It turns out that my vehicle had a bad EGR valve which was causing my car engine to misfire. Coincidentally, the most likely symptom of a bad EGR valve is also when the engine misfires. Other symptoms might include the engine management light coming on, the car stalling when idling, the fuel efficiency getting worse, or the car under-performing.

I started researching this topic, and I found that the most likely symptom of a bad EGR valve is when the engine misfires, but thankfully, it can be fixed. There are other less likely symptoms as well, that I’ll be talking about below, so if you’d like to learn more about all the symptoms of a bad EGR valve, keep on reading.

What Is an EGR Valve and What Does It Do?

An EGR valve is a device that helps to reduce emissions from an internal combustion engine. It does this by allowing some of the exhaust gases to be recirculated back into the cylinders, where they have burnt again. This reduces the number of harmful pollutants that are emitted into the atmosphere.

The EGR valve is located between the engine and the exhaust system, and it consists of a series of pipes and valves through which the gases flow. When the engine is running, these components open and close to allow just enough gas to be recirculated without affecting performance.

EGR Valve Works

Over time, soot can build up on the EGR valve, restricting its movement and causing problems with emission reduction. As well as impacting air quality, a dirty or faulty EGR valve can also lead to decreased fuel economy and increased wear on engine parts.

Regular cleaning or replacement of your vehicle’s EGR valve will help keep your car running smoothly and reduce your impact on the environment. Not doing so can result in your vehicle’s EGR valve becoming clogged and can even cause your vehicle’s engine to misfire.

Can a Bad EGR Valve Cause the Engine to Misfire?

A bad EGR valve can easily cause the engine to misfire. The exhaust gas re-circulation (EGR) system redirects a small number of exhaust gases back into the engine cylinders. This helps to reduce emissions and improve fuel economy.

However, if the EGR valve is stuck open, it can allow too much exhaust gas into the cylinder, causing a lean air-fuel mixture.

This can lead to an engine misfire. When this happens, the engine will usually run rough and may produce a knocking noise and decreased power. The engine can even stall or refuse to start. Since it’s not a good idea to keep a bad EGR valve inside of your vehicle, you might be wondering if it’s a good idea to just disable it instead.

What Will Happen if the EGR Valve Is Disabled?

If you disable your EGR valve, it can cause your engine to run less efficiently and produce more harmful emissions that will damage the environment. Additionally, it can lead to increased wear and tear on engine components, potentially causing damage or even fail over time.

In short, if you disable your EGR valve, be prepared for potential problems down the road.

It should also be mentioned that it is highly illegal to do so in all 50 US states. If caught, you may be subject to fines or other penalties such as getting your car’s registration card taken away.

Before making any changes to your EGR valve, check your local laws and regulations to ensure you are not violating any rules and putting yourself at risk. Since it’s not such a good idea to disable your EGR valve, you might be wondering if it’s safe to drive with a bad EGR valve.

Is It Safe To Drive With a Bad EGR Valve?

It’s safe, but not recommended, to drive with a bad EGR valve, since driving with a bad EGR valve can cause your engine to run less efficiently and produce more emissions. Additionally, your car will not run as smoothly and shake while it’s idling.

Since the EGR valve helps regulate the number of exhaust gases that re-enter the combustion chamber, driving with a bad one can decrease fuel economy and increase pollution. If you’re driving with a bad EGR valve, you might notice a few symptoms associated with it.

Symptoms of a Bad EGR Valve

Your Vehicle’s Engine Misfires 

One of the symptoms of a bad EGR valve is an engine misfire. An engine misfire is when one or more of the cylinders in an internal combustion engine fails to fire properly. This can happen for several reasons, including spark plug problems, fuel injection problems, compression issues, or cylinder head damage.

Engine misfires can cause all sorts of driving problems, from reduced power and poor gas mileage to increased emissions and even complete engine failure. If your vehicle is not experiencing an engine misfire due to a bad EGR valve, another symptom would be the engine management light coming on.

The Engine Management Light Comes On

If your engine management light comes on, it could be a symptom of a bad EGR valve. The engine management light is a warning system that comes on to indicate that there’s an issue with your car’s EGR valve. If your vehicle’s engine management light isn’t coming on, another symptom would be your car stalling when it’s idling.

Stalls When Idling

If your car stalls when idling (like we explained in the Mazda CX-5), it could be a sign of a bad EGR valve. This can happen because when your engine is running, exhaust gases are constantly being produced and expelled through the EGR valve. Over time, these gases can build up and cause the valve to become stuck open permanently.

This means that exhaust fumes are constantly being drawn into the combustion chamber, thus causing the engine to stall when it’s idling. If you don’t see your car stalling when it’s idling, you might see another symptom, which could be your fuel efficiency getting worse.

Fuel Efficiency Gets Worse

If your vehicle is getting worse fuel efficiency than usual, it could be a sign of a problem with the EGR valve. If fuel efficiency worsens, it means that less energy is being produced from a given quantity of fuel.

In other words, your vehicle is getting fewer miles per gallon which leads to an increase in pollution levels. If your fuel efficiency doesn’t get worse, another symptom would be your car having poor performance.

The Car Having Poor Performance

Your car’s performance can suffer for a number of reasons, but one potential cause is a bad EGR valve. In your car, poor performance can manifest in several ways. For example, the car can have reduced power and torque, which results in slower acceleration and lower top speeds.

Additionally, the engine may make strange noises or run roughly, indicating that it is not running as efficiently as it should be. After you’ve finished reading about all the possible symptoms of a bad EGR valve from above, you might be wondering if there are any reliable ways to test for it.

How To Test for a Bad EGR Valve?

You will need one or more of the following tools to test for a bad EGR valve:

  • OBDII scanner
  • multi-meter
  • vacuum gauge
  • automotive scan tool
  • manual vacuum pump

Preliminary Steps

The first thing you should do is use your OBDII scanner to scan your vehicle. The OBDII scanner is a handy tool that can be used to diagnose and troubleshoot many different automotive issues. One of the things it can be used for is checking whether or not an EGR valve is working properly.

If you think your vehicle might have a bad EGR valve, here’s how you can use an OBDII scanner to check it out. First, start by hooking up the OBDII scanner to your vehicle’s diagnostic port. Once it’s plugged in, turn on the code reader and wait for it to power up. Then press the button for scanning.

The code reader will then scan your vehicle’s engine control unit for any stored codes. If it finds a code related to the EGR valve, it will display it on the screen. Next, you’ll need to interpret the code. Each code has a specific meaning, so you’ll need to consult your OBDII scanner’s manual or an online database to find out what the particular code you’re seeing means.

If the code indicates that there is a problem with the EGR valve, then it’s likely that it needs to be replaced. If you cannot find anything wrong with your OBDII scanner, then you can try a visual inspection instead.

Visual Inspection

A visual inspection of the EGR valve itself can be helpful in diagnosing a problem, and if you suspect there is an issue, you can check to see if there is any exhaust leaking from around the EGR valve. If so, this is a good indication that the valve needs to be replaced.

Another thing to look for is a build-up of carbon deposits on or around the EGR valve, as this can indicate that the valve isn’t operating correctly and needs to be cleaned or replaced as well.

You should also check out the vacuum line that runs from the valve to the engine, as this line can become disconnected or blocked, thus preventing the EGR valve from operating correctly. If doing a visual inspection doesn’t come up with anything, you can try to do an electrical test using a digital multi-meter.

Electrical Tests

If you’re having issues with your car’s engine, one thing you can do to check if the problem is with the EGR valve is by using a digital multi-meter. This test will help determine if there’s an electrical issue causing the valve to not function properly. Here are some steps on how to go about it:

  1. First, locate the valve itself. It should be near where the exhaust manifold meets up with the intake runners. If you’re unsure of its exact location, consult your car’s documentation or look for diagrams online specific to your make and model.
  1. Once you’ve found it, disconnect any wiring harnesses that may be attached to it so that you can access it more easily.
  1. Now set your multi-meter device to measure DC voltage and touch each of the exposed terminals on the EGR wire connector leading into/out of this sensor while someone else operates revs up RPM from idle until just before hitting the red line then returns back down again. Make sure to also take note of what average standing motor voltages were measured at various throttle percentages between 0% to 100%.

If you’ve done all the tests above on your EGR valve and found a problem with it, you might be wondering about how to replace the EGR valve by yourself without having to take it to a mechanic.

How to Replace the EGR Valve?

Step 1: Locate the EGR Valve

Locate the EGR valve on your engine. It is usually located near the throttle body, intake manifold, or firewall. In some cases, it may be necessary to remove other components such as an air cleaner or battery tray to access the EGR valve.

Step 2: Disconnect the Electrical Connector

Once you have found the EGR valve, disconnect any electrical connectors that are attached to it. To do so, use a wrench or pliers to loosen the bolts or nuts that hold it in place. With the bolts loosened, you should be able to wiggle the connector free.

Step 3: Disconnect the Vacuum Line

Next, disconnect the vacuum line that is connected to the EGR valve. This will usually be a small diameter hose. Once you have located the vacuum line, use the appropriate wrench or socket to loosen and remove any clamps or fittings that are holding it in place.

After that, gently pull on the vacuum line until it comes free from the EGR valve port. It may also help out if you wiggle it back and forth as you pull.

Step 4: Remove the Mounting Bolts

Once the electrical connector and vacuum line have been disconnected, you can remove the mounting bolts that hold the EGR valve in place. Usually, there are only 2 to 3 of them. Be careful not to lose these as they are sometimes difficult to find when putting everything back together.

Step 5: Clean the Mounting Surface

With the bolts removed, gently pull the EGR valve away from its mounting surface taking care not to damage any surrounding components. Once it is free, inspect the mating surfaces for any debris or buildup and clean them as necessary with the required tools.

Step 6: Install the New EGR Valve

To install the new EGR valve, simply reverse the steps above making sure that all connections are tight and there are no leaks present before you move on to the next step.

Step 7: Test for Leaks

The next step is to test for leaks. This can be done by starting the engine and monitors vacuum gauges or pressure readings while checking for any drops in intake manifold pressure. If there is a sudden drop, then there is most likely a leak in the system.

Step 8: Check Out the Check Engine Light

For the last step, you should take a look at the check engine light to determine if everything is working properly. The check engine light should not be illuminated if everything looks good and there are no leaks.

Why Do EGR Valves Get Stuck Open?

The most common reason why EGR valves get stuck open is due to carbon buildup on the valve and in the EGR system itself. This can happen over time as the engine burns fuel, and it can also be caused by using low-quality fuels or additives that leave behind residue.

If an EGR valve becomes stuck open, it will cause increased emissions from the engine and may result in reduced performance or fuel economy. In some cases, it could even lead to damage to other components in the engine if not addressed quickly enough.

If you’re wondering if there’s anything you can do to prevent your EGR valves from getting stuck open, there is. One way to prevent your EGR valves from getting stuck open is to simply clean them properly from time to time. But how do you do that?

How Often Should You Clean an EGR Valve?

It is recommended to clean your EGR valve out at least once a year. If you are mostly driving your vehicle in the city without spending too much on the highways, your EGR valve will get dirty much sooner than if you mostly driving on the highways.

Take note that if you live in an area with a lot of smog or other air pollution, that can also easily shorten the lifespan of your EGR valve, so make sure to consistently clean out your EGR valve at least once a year.

How To Clean an EGR Valve Correctly?

Tools you will need:

  • a can of carburetor cleaner
  • a stiff wire brush
  • rags or paper towels
  • gloves (optional)

It is important to regularly clean your EGR valve to keep it in good working condition. Here are the steps you need to take to properly clean an EGR valve:

  1. Take off the negative terminal from your car’s battery.
  1. Remove any vacuum hoses or electrical connectors from the EGR valve.
  1. Using carburetor cleaner and a stiff wire brush, scrub all of the carbon deposits off of the surface of the EGR valve. Be sure to get into all of the nooks and crannies.
  1. Wipe away any remaining cleaner with rags or paper towels until the surface is completely dry.
  1. Reattach any hoses or connectors that were removed in the first step.

If cleaning the EGR valve doesn’t help out in the least, you could try replacing it entirely.

Average Cost for Replacing a Bad EGR Valve

The cost of replacing an EGR valve will vary depending on the make and model of your vehicle. However, you can expect to pay anywhere from $200 to $1,000 for the parts and labor involved.

Here’s a graph detailing the cost of replacing a bad EGR valve for the top 10 popular vehicles:

Vehicle ModelEGR Fitting Labor CostReplacement EGR CostTotal Cost
Ford F-Series$40 – $60$160 – $220$200 – $280
Chevrolet Silverado$30 – $40$230 – $365$260 – $405
Ford Focus$80 – $100$120 – $220$200 – $320
Toyota Camry$50 – $70$270 – $300$320 – $370
Toyota Corolla$80 – $100$260 – $400$340 – $500
Nissan Altima$30 – $50$190 – $230$220 – $280
Honda CR-V$75 – $100$220 – $370$295 – $470
Honda Civic$50 – $70$250 – $320$300 – $390
Honda Accord$50– $70$210 – $280$260 – $350
Ford Fusion$70 – $100$170 – $190$240 – $290

Disabling The EGR Valve

It’s not legal to disable your EGR valve in all 50 states in the US. The reason for this is that the EGR valve helps reduce emissions by recirculating exhaust gases back into the engine. By disabling the EGR valve, you are increasing your vehicle’s emissions and harming the environment.

If you want to improve your vehicle’s performance, there are other ways to do it that don’t involve breaking the law. However, if you insist on wanting to know how you can disable your vehicle’s EGR valve, keep on reading.

We do not recommend this, but If you insist on disabling your EGR valve, Here’s how:

How To Disable the EGR Valve?

  1. Locate the EGR valve on your engine. It will typically be located at the top of the engine, close to the intake manifold.
  1. Disconnect the vacuum hose that is attached to the EGR valve. This will prevent any vacuum pressure from reaching the valve itself.
  1. Remove the parts holding the EGR valve in place, and then remove the EGR valve from your vehicle.

Instead of disabling the EGR valve, if you would rather just clean it, you might be wondering about how often you should be cleaning it.