Symptoms Of A Bad Purge Valve – How To Know Test It

In a car’ engine, a purge valve plays a crucial role. It is a component of the EVAP system (or Evaporative Emission Control) and keeps gasoline vapors from leaking into the atmosphere.

Your car may have several issues when the valve isn’t functioning properly. Therefore, it is necessary to know the symptoms of a bad purge valve as it might help you fix the issue before it worsens.

This post will walk you through all the basics of this car’s essential component, from what it is, how it works to the signs of its malfunctioning.

It will make it easier for you to comprehend how crucial it is and why your car needs to be replaced when it stops maintaining its condition.

About Purge Valve

Symptoms Of A Bad Purge Valve

What Is It?

The primary purpose of a purge valve, which is a part of the system regulating evaporative emissions, is to transfer the stored vapors from the charcoal canister into the engine.

The charcoal canister holding the gasoline vapors and the intake manifold are connected by a vacuum line.

When necessary, these vapors can enter the intake manifold thanks to the purge valve located inside the vacuum line.

Purge valves are operated by vacuum in older cars, while electronic control is used in more modern ones.

How Does It Work?

Fuel vapors have access to the intake manifold when your purge valve opens.

The vapors are then transported to your internal combustion engine, where they are introduced to the air and fuel combination and then ignited.

The engine control unit is responsible for managing any electronic purge valves you may have.

The main computer of the car uses this to determine the precise volume of vapor that should be injected into the motor.

The valve will close when it has let enough vapor through, preventing any more vapor from passing. The vapor will simply accumulate within the charcoal canister as soon as it is no longer required.

Symptoms Of A Bad Purge Valve

Bad Purge Valve

The clearest sign of a bad purge valve is the Check Engine light coming on, followed by rough idling, difficult starting, fuel smells, bumpy acceleration, failing emissions test, and other engine performance problems.

Your purge valve will deteriorate over time and lose efficiency, and it may even crack due to adverse environmental conditions, just like other automobile parts.

Illuminated Engine Check Light

A worn-out or damaged purge valve may set off the Check Engine light warning. This is because the purge valve’s operation is detected by sensors.

However, if the valve stops sending signals, your sensors will assume that the valve is malfunctioning. 

Your vehicle will then display the intermittent flashing Check Engine warning as a result of the sensors relaying this data to the engine management unit.

Rough Idle Or Engine Stall

The engine in your car no longer operates smoothly when it has a rough idle. It will run irregularly while you’re driving, especially when you stop at the red light.

Your motor will operate more inconsistently the longer you leave this issue unattended. Your engine stalling completely will be the worst scenario.

Try to prevent things from getting out of control. When your purge valve is the cause of the bumpy engine idle, it frequently results in a vacuum leak, affecting the idle speed.

Check out our post on rough idle when AC is on to learn more about this problem.

Engine Performance Issue

Be prepared for a bumpy ride when your car can start despite having a defective purge valve. Your engine’s performance will undoubtedly deteriorate.

To put it another way, the acceleration you want as you depress the gas pedal won’t be possible because the engine won’t have the same amount of power.

This will be most noticeable when climbing hills or trying to pass another car.

Trouble Starting Vehicle

You’ll most likely have trouble with the engine starting process if there is a vacuum leak caused by a malfunctioning purge valve.

This will lead to the engine’s intake of outside air being uncontrollable, which will disrupt the process of internal combustion as a whole.

Engine issues are unavoidable when unmetered air and fuel mingle inside the engine cylinder chamber.

Failed Emissions Test

As you are already aware, the purge valve is in charge of rerouting fuel vapors into the car’s engine. This stops your tailpipe from emitting harmful hydrocarbons.

Because of this, when the purge valve was to break down, it would be unable to reroute the fuel vapors and keep them from fleeing your automobile.

This will become clear to you when your car fails the emissions test.

Suppose this occurs; ask the expert auto mechanic to examine your purge valve to determine whether the component is to blame for the unsuccessful emissions test.

It would be best if you replaced it right away in case it is worn out or damaged. The emissions test should be passable at that point.

Fuel Smell In The Engine

On the majority of contemporary automobiles, fuel injectors positioned in the intake or implanted into the motor spray an exact quantity of fuel during each cycle.

Fuel leakage and a strong gasoline odor in the engine are signs that the purge valve isn’t shutting properly.

The best course of action is to examine the purge valve in case you notice any weird engine smells.

Damaged Gaskets

Gaskets are a common way to seal and cushion gaps between surfaces that are fastened together with bolts in automobiles.

When undertaking significant engine work, professional auto mechanics frequently replace a gasket.

Pressure will accumulate in the car’s combustion chamber when the purge valve is trapped shut, eventually damaging the gasket and destroying the rubber seals.

Bumpy Acceleration

A lack of spark, air, or fuel during combustion typically triggers an acceleration issue. If you press the gas pedal and the vehicle takes a few seconds to accelerate, your purge valve is probably broken. 

A properly working purge valve can clear the engine of extra gasoline and fumes, enabling smooth acceleration.

How To Test Your Purge Valve

Using the steps below, you can check a purge valve’s functionality by measuring the resistance between its terminals with a multimeter.

Keep in mind that although the specific steps may vary depending on the automobile model, testing the purge valve generally follows the same process.

Step 1: Turn off your engine and give it roughly 30 minutes to cool down.

Step 2: Find the purge valves. They should ideally be placed on top of the muffler or behind it.

Step 3: Identify the purge valve by looking for a 2-pin harness that connects to it. Purge terminals should be reconnected to adapter cables on the multimeter after the harness has been disconnected.

Step 4: You ought to receive a reading from the multimeter. Typically, a purge valve should function properly when the multimeter value is between 22 and 30 ohms.

The purge valve must be replaced if the reading falls within or exceeds this range.

Frequently Asked Questions

How Long Can A Purge Valve Last?

The purge valve’s lifespan will depend on your driving habit and how regularly it is maintained.

Although ideally, it should be as long as the vehicle itself, it may become worn out like other car parts do every few years.

Can I Drive With A Malfunctioning Purge Valve?

Yes. Even when the purge control valve is broken, you can still drive the car to the repair shop without noticing any serious performance problems.

Still, it is not advised to continue driving when the purge valve is broken without having it fixed.

It can be detrimental to the environment and the performance of your car for the purge valve to malfunction because this will allow pollutants to exit.

Is It Costly To Replace A Purge Valve?

The price for replacing a purge valve is quite reasonable. Depending on the model of the car, the typical cost to replace a purge valve ranges from 151 to 172 dollars.

Predicted labor costs range from 42 to 53 dollars, while parts are expected to come at the price of 109 to 119 dollars.

Should I Replace The Valve On My Own?

Although replacing a purge control valve is not too difficult on the majority of car models, it can be challenging to DIY.

You can replace the valve on your own, but you will need basic knowledge of repairing cars to be able to perform the replacement correctly.

If this is not the case, it is advisable to bring your car to a repair shop and let the experienced mechanic handle the problem.

The Bottom Line

A purge valve is combined in the EVAP system to help lower carbon emission levels.

It greatly cuts emissions when every vehicle component is operating as it should. You will begin to notice the symptoms of a bad purge valve if it malfunctions.

When you do, it would be best to take your car to a repair shop as soon as possible to get it fixed.

This way, you can prevent further damage and unnecessary repair expenses.

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