Common Symptoms Of A Bad Evap Canister

Modern vehicles are designed with a lot of emission systems. Amongst these systems is an EVAP (Evaporative Emission Control) system. This system closes in fuel vapors and prevents the vapor from escaping into the environment. Hence, reducing gas emissions. The EVAP canister is one of the key components in this system. So, it’s essential you know the symptoms of a bad evap canister in your system to enable you service your vehicle on-time, and save yourself from high repair costs.

Symptoms Of A Bad Evap Canister

Common Symptoms Of A Bad Evap Canister

When you have a lousy EVAP canister, it will generate issues with your Evaporative Emission Control System, negatively affecting your vehicle’s emission output. A faulty EVAP canister often exhibits these highlighted symptoms, signifying the driver of a problem in the vehicle, which needs to be fixed.

Poor Gas Mileage

A low gas mileage indicates that your vehicle is not operating at optimum efficiency. It also signifies that there is a high consumption or leakage of gas in your vehicle’s system. Several factors can make your vehicle have low gas mileage, including a lousy EVAP canister. In this case, this happens because the fuel vapors your vehicle usually uses during combustion gets burned up to the environment before getting to the combustion chamber.

This means that you will lose some amount of your gas usually used during combustion, which causes your vehicle to have low gas mileage, increasing your budget on buying gas for the vehicle. This can get your vapor canister saturated or clogged.

Poor Engine Performance

A damaged EVAP canister is bound to cause poor engine performance. Your engine will begin to have a less effective operation, producing a low power for high acceleration. This might cause your vehicle to have a sluggish movement, even as you apply pressure on your gas pedal.

An incomplete combustion process generated due to a bad EVAP canister will cause your vehicle to have a sluggish acceleration, which you have to address immediately to prevent any undesirable condition.

Difficulty in Starting Up the Engine

Difficult starting is also amongst the symptoms indicating your vehicle has a bad EVAP canister. This is due to a vacuum leak developed from issues with your charcoal canister, and it might make your vehicle’s engine difficult to kick-off. When you have a vacuum leak, it will permit unmetered air into your engine, which can unbalance the mixture of the air-fuel ratio, which will develop issues in your engine’s system by disturbing the internal combustion process. If this fault is left to continue, it can eventually lead to your vehicle not starting.

An unbalanced air-fuel ratio during combustion can lead to improper combustion due to a high amount of air in the engine.

Engine Check Light Turns ON

Your engine check light will come ON when you have a damaged EVAP canister. If your vehicle’s computer system detects a fault within your EVAP system, it will illuminate the engine check light to tell the driver that there is an issue with the engine system.

The computer system picks up this fault via signals from your EVAP system. However, the engine check light can turn ON as a result of several other problems, so it’s advisable to properly scan your vehicle for error codes with an OTC Leak Tanner or Use another Smoke machine to get the actual fault responsible for turning the engine check light ON.

Rough Idling

A prevalent symptom of a damaged EVAP canister is when your vehicle has a rough idle. The vehicle will not be able to maintain a high speed due to an unstable rpm count, or you might feel a shaking sensation in your vehicle while driving. Usually, your vehicle should have a stable rpm rate of about 1000.

If this rpm is fluctuating, there is a good chance you are looking at an idling issue. Rough idling can be due to faulty spark plugs, carburetor problems, dirty fuel injectors, and a vacuum leak.

A vacuum leak can occur as a result of a damaged or faulty EVAP canister or the hoses fixed to it. When you notice this symptom, you need to immediately attend to it, as it can severely damage your engine system.

Gas Odor

Gas odor is amongst an evap leak symptoms and can result from various faults or engine problems in your vehicle’s system, but one of the major causes is a broken EVAP canister. A damaged vapor canister can give out a strong gas smell when it is bad.

Failed Emission Test

Your vehicle will fail emission testing if you have a bad EVAP canister in your system due to emission of gas fumes. This type of fault will also illuminate the engine check light.

Gas Tank will get difficult to fill up.

When you fill-up your fuel tank, the released gas vapors is channeled to the EVAP canister and other relating engine components. If your canister is clogged, the vapor will not go into the canister. Instead, it will go back to your gas tank, making it difficult to refuel your tank.


Is it bad to drive with a bad EVAP canister?

Technically, it is quite safe if you are deliberating driving with a bad evap canister. This fault alone might not cause your vehicle to function poorly, but your vehicle will not pass an emission test with this problem. A bad EVAP canister will make your vehicle release a high amount of gas fumes, causing environmental pollution, and also keep your dash engine check light ON. However, when you notice an issue with your EVAP system, you need to get the problem fixed as soon as possible.

What does the EVAP canister do?

The EVAP canister is linked to your fuel tank through the line of the tank vent. The canister stores about 2 lb. of activated charcoal used to store and contain fuel vapors until your purge valves open up and allow the engine intake’s vacuum to absorb some fuel vapors from the charcoal into the intake manifold of your engine. This is done to reduce gas emissions from your vehicle.

Your EVAP canister can hold a high amount of fuel vapor when your vehicle is in good shape and operating at high efficiency. The fuel vapor goes into your engine to get burnt. This process is termed ‘purging,’ which needs to be assisted by the purge valve.

Your vehicle’s Powertrain Control Module starts the burning process by opening up your purge valve. The valve opening will draw in outside air over the charcoal and force fuel vapors into your engine. In the engine, the vapors are used up with the usual combustion process.

But you might be wondering, will my car run bad without a vapor canister? Well, yes, it would. A bad canister can cause poor engine performance affecting the vehicle’s acceleration.

How do you test a canister purge valve?

The proper way to test your canister purge depends on your vehicle’s repair guide. This procedure varies for different types of vehicles, depending on the model. In some vehicles, you have to apply voltage to the valve terminals in some vehicles and see if it makes a clicking sound. If you get that sound, then your canister purge valve might be alright.

Then you also have to attach a vacuum pump to the purge valve and apply pressure. This is to know if the valve isn’t leaking and closes correctly. Immediately after the pressure drops, the vacuum should close. If not, it has to be replaced.

Can the EVAP system cause a car not to start?

A minor case of a bad EVAP system would not cause your vehicle not to start, like a small leak or minor tear. But if the faults accumulate, it can cause your engine to shut down eventually.

How much will it cost to repair an EVAP leak?

Evap canister replacement cost can be between $100 to $600. The cost of repair depends on two factors: the leakage location and the cause of leakage. However, other causes require a minor repair to fix, which will not cost so much. But if the repair requires the replacement of various components in your EVAP system, it can build up to a high repair cost. Your vehicle’s model is also a determining factor of how high your repair cost will amount to.

The price of automobile parts varies, depending on the model. Some vehicle models will demand a high-priced part, while others are reasonably affordable or cheap. If your vehicle has an EVAP leak due to some faulty parts, it is better to have those parts replaced. Repairing the damaged parts usually is less expensive, but it gives a short-term solution. Of course, service costs also vary, which means a huge difference in the finalizing the cost of fixing this issue.

If you are thinking of how to bypass evap canister or other components in your system to evade the cost, it will expose your vehicle to more troubles, especially when it is not done correctly.

What is the difference between an EVAP canister, a Vapor Canister, and a Charcoal Canister?

There is no difference between these three canisters, and you can interchange the names. The naming depends on the manufacturer of the vehicle. The EVAP canister can be called a Vapor canister or a Charcoal canister.

Final Words:

The EVAP canister is an integral part of your EVAP system, so you need to get yourself acquainted with the symptoms of a bad evap canister listed above to keep your vehicle eco-friendly and running at high efficiency.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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