The combustion chamber can reach over 1300 degrees F when your engine is at operating temperature, and those conditions are ripe for mechanical failures and increased emissions.
Your engine is equipped with an EGR valve, or exhaust gas recirculation valve, to mitigate the effects of extreme heat as your engine runs.
But an EGR valve isn’t failproof, even though it typically lasts around 10 years trouble-free. If it fails, you’ll experience a handful of symptoms that indicate you’ll need to replace it.
Prices will range a great deal depending on what vehicle you own with some coming in under $50. While many are quite a lot more, you can expect the average price to be around $90 plus any associated labor charges and incidental parts.
What does an EGR valve do, and what are the symptoms of a bad EGR valve? Learn that, plus what causes it to go bad and if there are ways to prevent it.
What Is an EGR Valve and How Does It Work?
An engine’s ignition and combustion process requires a precise air-fuel mixture to power the pistons. However, this process generates a lot of heat and harmful nitrogen oxide (NOx) emissions.
The exhaust gas recirculation valve (EGR valve) redirects some of these exhaust gasses back into the combustion chambers to reduce your car’s nitrogen oxide (NOx) emission.
Here’s how it functions:
The EGR valve operates in two main settings:
- It stays closed when the engine starts
- It opens when it’s idling or running at low speeds
When the engine is under partial load, like during idling, the Engine Control Module (ECM) signals the EGR valve to open. This allows the exhaust gasses to mix with fresh air and fuel in the intake manifold before entering the combustion chamber.
Now, exhaust gasses don’t burn like fresh air-fuel mix. There is a lesser concentration of oxygen in the exhaust gasses, which helps lower the peak combustion temperature. Since NOx usually forms at high temperatures during combustion, the introduction of inert exhaust gasses helps reduce NOx emissions.
Wondering how to spot a failed EGR valve? Let’s find out.
Bad EGR Valve Symptoms
Here are the 8 common signs of a failing EGR valve:
#1. Rough Engine Idle.
An EGR valve stuck in the open position allows an excessive amount of exhaust gas to flow back into the combustion chamber.
This results in an improper air-fuel mixture due to exhaust gas displacing atmospheric air in the combustion chamber, reducing oxygen content in the air-fuel mixture.
This condition causes the engine to idle roughly.
#2. Illuminated Check Engine Light.
The Engine Control Module (ECM) controls the operation of the EGR valve, as well as the illumination of the Check Engine Light.
In cases where a vehicle displays one or more symptoms such as those described above and the Check Engine light illuminates, it may indicate a faulty EGR valve.
If the ECM detects that the air/fuel mixture is incorrect, or that the EGR valve does not move properly to its commanded position, it will set a Diagnostic Trouble Code (DTC). DTCs associated with a faulty EGR valve include P0300, P0100, P0101, P0102, or P0104.
#3. Stalling.
If an EGR valve has failed in the open position, it has the tendency to cause stalling at idle. This is due to the fact that a large amount of unmetered exhaust gasses are allowed to enter the intake tract at all times, essentially producing a significant vacuum leak.
#4. Starting Difficulties.
You might also notice that your car has become harder to start if the engine’s EGR valve has failed in the open position. This occurs for much the same reasons as mentioned above.
Significant exhaust gas recirculation at low temperatures or at start-up can substantially impair an engine’s ability to run as intended.
#5. Engine Knocking or Pinging Sounds.
When the EGR valve is stuck closed, it prevents the recirculation of exhaust gasses. Consequently, the temperature in the combustion chamber keeps rising and exceeds the threshold for proper combustion.
As a result, the fuel ignites earlier than it should, especially at low RPMs. This untimely fuel combustion may cause engine knocking or a pinging sound.
Note: Ignoring this symptom can also damage other vehicle components, like the spark plugs.
#6. Increased Fuel Consumption.
The exhaust gas recirculation valve opens and closes based on the throttle movement and exhaust manifold vacuum.
When carbon deposits build up in the valve, the EGR valve can stay stuck open, allowing exhaust gas to re-enter the combustion chamber at the wrong time.
It can also result in a vacuum leak in vacuum-operated EGR systems. This again affects the fuel economy as the engine tries to compensate by increasing fuel consumption.
#7. The Smell of Fuel
Even under normal operating conditions, NOx emissions exiting the tailpipe have a strong, noxious odor, which is both unpleasant and unhealthy. A malfunctioning EGR valve can cause the engine to consume more fuel.
This results in an increase in NOx and unburned hydrocarbon fuel emissions passing through the engine and out the exhaust pipe. These emissions can be detected at the back of the vehicle, and even in the cabin.
#8. Excessive Emissions
While several factors can contribute to a vehicle failing an emissions test (including malfunctioning fuel injectors or oxygen sensor, a loose gas cap, or a dirty air filter), a faulty EGR valve is another potential cause that should be considered.
The primary function of the EGR valve is to reduce vehicle emissions. Any malfunction in the EGR valve can cause an increase in vehicle emissions, making it more likely for the vehicle to fail an emissions test.
Causes of EGR Valve Failure
Bad Fuel
Low-quality or contaminated fuel can contribute to the deterioration of the EGR valve. Impurities in the fuel can cause deposits to build up within the valve, hindering its ability to open and close correctly.
This can lead to reduced engine performance, increased emissions, and potential damage to the EGR valve itself.
Lack of Maintenance
Neglecting regular maintenance of your vehicle can contribute to EGR valve failure. Over time, carbon deposits can accumulate within the valve and its associated components, restricting the flow of exhaust gases and negatively impacting the valve’s functionality.
Faulty Parts
A bad EGR valve may also be caused by issues with the surrounding components, such as the EGR solenoid, vacuum hoses, or electrical connections.
A bad EGR solenoid can prevent the valve from opening or closing properly, while damaged vacuum hoses or electrical connections can disrupt the communication between the valve and the ECM.
Manufacturing Defects
Though rare, manufacturing defects can also cause EGR valve issues. In such cases, the valve may be faulty from the start, leading to poor performance or premature failure.
Extreme Operating Conditions
Exposure to extreme operating conditions, such as high temperatures, excessive dust, or prolonged periods of heavy load, can hasten the wear and tear on an EGR valve.
These conditions can lead to accelerated carbon buildup and increased stress on the valve components, potentially causing premature failure.
EGR Valve Replacement Cost
The average cost for an EGR Valve Replacement is between $387 and $470. Labor costs are estimated between $95 and $120 while parts are priced between $293 and $351.
This range does not include taxes and fees, and does not factor in your unique location. Related repairs may also be needed.
The exact price associated with EGR valve replacement often differs from one make and model of vehicle to the next, due in large part to variances in parts costs and applicable labor expenses.
This discrepancy in cost can be reduced to a certain extent when choosing to tackle the labor required for this job in a DIY fashion.
Generally speaking, you can expect to pay between $150-$550 to have your vehicle’s EGR valve replaced, with parts costs accounting for $100-$450 of this total expenditure.
It’s worth noting, however, that certain outliers exist, falling well north of this price estimate. This is often the case with vehicles of foreign make or those that are performance-oriented in nature.
Can You Continue Driving With a Bad EGR Valve?
In certain cases, yes, it is possible to continue driving with a faulty EGR valve, though doing so is not recommended.
In other cases, a vehicle might not remain operable with a failed EGR valve, due to the severity of driveability-related symptoms that are incurred. The difference between these two scenarios centers around the manner in which the EGR valve has failed.
If a vehicle’s EGR valve fails in the open position, performance will likely be erratic, with stalling/no-start occurrences not being out of the question. This is because of the tendency of a stuck-open EGR valve to act as or create a monumental vacuum leak of sorts, allowing unmetered air into the combustion tract.
On the other side of the coin, it is possible for a vehicle with an EGR valve that is stuck closed to operate with little in the way of secondary symptoms, though even this is not guaranteed.
Always address EGR-related issues promptly, regardless of the situation. Quick evaluation and repair maintains optimal engine performance and helps avoid unexpected breakdowns. Those who are not comfortable with tackling such repairs should seek out a quality service center for assistance.
What Is an EGR Delete? Is It Worth Doing?
An EGR Delete involves removing a vehicle’s EGR valve, before plating off the flange to which it is typically affixed. This modification eliminates the recirculation of exhaust gasses through an engine’s intake manifold.
Proponents of this modification have cited improved engine performance, smoother idle, and increased reliability.
However, it is important to keep in mind that there are several drawbacks to performing an EGR delete as well. Most noteworthy is the fact that performing this modification will make it nearly impossible to pass state-mandated emissions testing.
Additionally, the removal of any factory-equipped emissions compliance device can lead to legal and/or warranty complications as well.