What Is A Purge Valve On A Car? new for 2022

What Is A Purge Valve On A Car?
What Is A Purge Valve On A Car?

Many car owners don’t know what is a purge valve in a car, or what it does. A purge valve is an important part of your car’s emissions system. If it isn’t working properly, your car may not be able to run correctly.

We can help you figure out What Is A Purge Valve On A Car? And we’ll show you 5 Bad Purge Valve Symptoms.


What Is A Purge Valve On A Car?

What Is A Purge Valve On A Car?
What Is A Purge Valve On A Car?

What is a purge valve in a car? The purge valve, also known as the canister purge valve, is a component of your vehicle’s EVAP system.

The purge valve in recent models is an electronically powered solenoid controlled by the engine computer. When you turn off your engine, the valve closes. Once your engine is up and running, the computer gradually opens the purge valve. This permits, fuel vapor to flow from the charcoal canister to the engine and burn. All of these components are linked together via a hose to form the EVAP system. Dust and debris, like many other car components, can block the canister. The purge valve may potentially shatter due to extreme environmental conditions. If the purge valve breaks, it might cause issues with the EVAP system, lowering your car’s emission output level.

Function of a purge valve

What does a purge valve do on a vehicle? When the engine is running, the purge valve opens to allow fresh air to enter the canister and push the vapors into the engine to be burned. In most cases, the purge valve is controlled by a solenoid that’s operated by the ECU.

The EVAP system is designed to keep fuel vapors from escaping into the atmosphere. Fuel vapors are highly volatile and can be extremely harmful to the environment.

In fact, evaporative emissions are one of the main contributors to smog and air pollution.

Definitions of Terms Relating to Purge Valve


In order for combustion to take place, an exact ratio of air and fuel must be drawn into the combustion chamber. Each engine has its own specific ratio that is adjusted by the engine control unit (ECU). The air-fuel mixture is the term used to describe this ratio.


Emissions are the gases that escape from a vehicle’s exhaust pipe during the gasoline combustion process.

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Check Engine Light/Code

Inside every vehicle, there’s a computer that closely monitors the performance and condition of several components. If something isn’t working right, the computer will generate a code that tells us what the problem is. In most cases, an error code will also cause a check engine light to come on in the gauge cluster. That way, you’ll know there’s an issue that needs to be fixed.

5 Bad Purge Valve Symptoms

Bad Purge Valve Symptoms
Bad Purge Valve Symptoms

The Check Engine Light is illuminated.

The check engine light is the first indication that anything is wrong with your canister purge valve. Your car’s computer controls your canister purge valve, allowing it to check its operation. If your vehicle’s computer senses higher or lower than normal purging from the valve, the check engine light will illuminate. P0441 and P0446, as well as other EVAP codes, are common error codes. If your check engine light comes on, take your vehicle to a skilled technician who can assist you determine the problem.

Reduced Gas Mileage

Your gas mileage may suffer if your canister purge valve does not open correctly. The reason for this is that the vapors produced by your car’s ordinary combustion will enter the EVAP canister and eventually be vented to the atmosphere, resulting in a loss of some of the fuel utilized in combustion.

Engine Issues

However, if your canister purge valve is jammed open, it causes a vacuum leak that might harm your engine. Simply said, air will be permitted to enter the engine in an amount that the computer in your automobile does not foresee. This will alter the car’s air-to-fuel ratio, resulting in rough idling (the car feels rough and bouncy when the engine is running) and difficulties starting. If these symptoms occur together, there is a good chance that a canister valve or another component of the EVAP system is malfunctioning.

Car Stating Problems

A bad canister purge valve is one possibility if your car isn’t starting. If there’s a leak in the vacuum, air from outside can get into the engine–preventing combustion. This problem is usually caused by  inadequately filtered air that mixes with fuel inside the cylinder chamber, resulting in an engine that is difficult to start.

The ticking noise

The ticking noise of the purge valve is most likely typical and should not be heard in the cab when the windows are up. If it’s too noisy inside, have the valve replaced. When you’re filling up with petrol, the purge valve may be leaking vapor into the engine and out through its tickling sound. To fix the situation, change out the purge valve.

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What causes purge valve failure?

What causes purge valve failure?
What causes purge valve failure?

Common Causes of Failure

If the canister or any supply lines are clogged or have holes, the solenoid will not be able to function properly and the purge control valve will stay closed. Additionally, the solenoid’s electrical components could fail, causing the valve to stay shut.

How much does it cost to replace a purge valve?

How much does it cost to replace a purge valve?
How much does it cost to replace a purge valve?

The cost of replacing a purge valve in your automobile is between $110 and $170, with the replacement parts costing an average of $75-$110, while the labor is generally only around $50, so this is a fast and simple repair that does not take long.

How to Test the Purge Valve (Solenoid)

How to Test the Purge Valve (Solenoid)
How to Test the Purge Valve (Solenoid)

The right process for testing the purge valve may be found in the vehicle’s service manual. The technique varies based on the brand and model of the vehicle. The purge valve in most automobiles is generally closed, which means it should be closed when no voltage is applied and open when electricity is applied.

Step 1:

Testing a purge valve, the service handbook suggests applying battery voltage to the purge valve terminals and listening for an audible click. To demonstrate, we just use a 9-volt battery. This purge valve emits an audible click.

Step 2:

The next step, according to the service handbook for this automobile, is to see that the purge valve closes correctly and does not leak. We connect a hand-held vacuum pump to the purge valve and apply suction.

Step 3:

When a purge valve is tested, the vacuum reduces almost quickly. This purge valve is not effectively sealing and must be replaced. On the dashboard, there was a “Check Engine” light. We had it scanned, and the code P0446 – Evaporative Emission Control System Vent Control Circuit Malfunction – was returned. We examined the EVAP system and discovered a slow leak. We’ve finally located the perpetrator!

Step 4:

To demonstrate the difference, we tested a purge valve from a different vehicle. It retains the vacuum really well, and the vacuum hasn’t fallen after one minute.

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Step 5:

Now we connect the battery voltage and test the purge valve. The vacuum lowers quickly when the purge valve clicks. This purge valve works well.

F.A.Q What Is A Purge Valve On A Car?

Does the purge valve affect gas mileage?

When a purge valve fails to open as it should, your gas mileage may be harmed. The vapors from your automobile’s combustion process will go to the EVAP container and be vented into the air, causing you to use fuel that would otherwise be burned inside your vehicle.

How long do purge valves last?

Normally, the canister purge solenoid lasts the lifetime of the vehicle. It’s possible for it to wear out from time to time. If you have a Check Engine light on and your car won’t pass an emissions test, it’s due to a failing canister purge solenoid.

Will a bad purge valve throw a code?

A faulty purge valve can cause your car to register a code. The most common codes are P0441 and P0446. In this scenario, it is probably that the purge valve solenoid is not completely closed or stuck open.

What happens if the purge valve is stuck open?

If your canister purge valve is blocked, it will create a vacuum leak that can damage your engine. This will alter the air to fuel ratio of the car, making it more difficult to start and producing harsh idling (the car feels rough and bouncy when it’s running).


A purge valve is an important part of a car’s emissions system. It helps to keep the fuel system clean and free from contaminants. If your purge valve is not working properly, it can cause a variety of problems with your car. Symptoms of a bad purge valve include poor performance, stalling, and difficulty starting the engine. If you think your purge valve may be causing problems with your car, have it checked out by a mechanic. If you have any questions, please contact to Amortips.com. We’re happy to support you.


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