5 Symptoms of a Bad Vapor Canister Purge Valve in Your Car

The vapor canister purge valve is a part of your vehicle’s evaporative emission control system. As your charcoal canister emits fuel vapor, the vapor canister purge valve regulates how much of this vapor emits from the canister. In older vehicles, a vacuum was what controlled the purge valve before onboard computers were introduced. Now, there is an engine control unit in virtually every new vehicle which serves as its central computer system. This computer electronically manages the functionality of the purge valve as well as the charcoal canister.

As a result, carbon emissions generated from the internal combustion process are redirected back into the combustion chamber where they are finally destroyed. The purge valve cannot function without the charcoal canister, and vice versa. Most of the time, these components functional beautifully and accurately because of the electronic control over them by the engine control unit. But that doesn’t mean malfunctions cannot take place sooner or later.

5 Common Symptoms

The vapor canister purge valve is prone to wear and tear or damage. Whether you’ve suffered a recent accident or simply owned your car for a long time, your purge valve may become faulty after a while. Then you will experience some unusual symptoms, but they will be symptoms which are worse than those experienced from a bad charcoal canister.

Below are the top 5 symptoms of bad vapor canister purge valve in your car. Once you start noticing these symptoms happening in your vehicle, you need to replace the purge valve immediately.

1) Car Won’t Start

When you have a bad vapor canister purge valve, it can easily cause a vacuum leak to occur. Because of this, you may find it difficult to start up your car. With a vacuum leak looming, uncontrollable amounts of external air will get into your engine and diminish the internal combustion process. In fact, it’ll likely cause you to have a lean air-fuel mixture. This is a sure recipe for a car that won’t start.

2) Check Engine Warning Light

A faulty purge valve can easily cause your check engine warning light to get activated by your engine control unit. After all, this computer receives information from various sensors about the status of the purge valve. If there is insufficient information about the purge valve being received, then it will cause the engine control unit to think something is wrong. This will cause the Check Engine light to come on.

3) Rough Idle

Your car engine doesn’t run normally anymore if it experiences a rough idle. Basically, this means the speed of your engine is inconsistent while it is running. It is even more inconsistent when you’re driving at lower speeds. Check the tachometer on your dashboard and you’ll see the RPM reading fluctuating profusely, especially when the engine is idle. If you don’t do something about this soon, your engine will stall out more often. This could be happening because your bad purge valve has caused a vacuum leak to affect the idle speed.

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4) Failed Emissions Test

A functional purge valve makes sure that fuel vapors are sent back to the engine after the internal combustion process takes place. That way, hazardous hydrocarbons won’t come out of your tailpipe. But if your purge valve is not functioning properly, then it’ll emit too many hazardous emissions. You won’t realize this until you get your emissions test and end up failing it. That is, of course, if you live in a state where emissions tests are required.

5) Weak Engine Performance

A bad purge valve weakens the performance of the engine. The acceleration of the vehicle will then be compromised when you step on the gas pedal. You need to replace your purge valve so that those fuel vapors can be redirected back to the engine. If there is a vacuum leak caused by the bad purge valve, you need to get that resolved too. Once these repairs are made, the engine should perform normally again.

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