Updated at: 12-08-2022 - By: Lucas

In order to keep the fuel system’s vapor leakage under control, the Evaporative Emission Control System (EVAP), charcoal, or vapor canister is used. Without this technology, the gasoline would evaporate even if the engine was not running. This has an enormous impact on reducing emissions. The EVAP canister, on the other hand, can become bad.

Most common symptoms include.

Engine light on, hissing sounds when fuel tank is opened, smell of gas inside cabin, difficulty with filling tank, and heavy smoke from exhaust pipe are all signs of a fuel leak in your car

How Does The EVAP System Work?

Symptoms Of Failing Evap Canisters

As an integral part of the fuel system, the exhaust gas aftertreatment (EVAP) system keeps the engine supplied with fuel while also preventing toxic fumes from escaping.

Vapors are always present in a fuel tank because of gasoline’s inherent volatile nature. There is a vent tube that directs them to an EVAP canister, where activated charcoal absorbs the vapors and allows them to exit the tank.

The purge flow sensor opens once enough vapors have been stored, allowing the vapors to enter the throttle body and be used as fuel. The EVAP canister’s vent solenoid will now open, allowing fresh air to enter and help balance the pressure inside.

Symptoms Of Failing EVAP Canisters

Symptoms Of Failing Evap Canisters-2

1. Hissing Sound

You may have heard a hissing sound when you opened the fuel tank to fill it up. When you’ve been driving for a long time, the EVAP canister is unable to equalize the pressure in time.

Even if the sound is very loud and you can feel the air going through, this indicates that there is not enough purification of vapors in the system.

2. Smell of Gasoline

A bad sign is if the vehicle smells of gasoline when you’re standing near it. As a highly flammable liquid, it vaporizes quickly and can ignite nearly spontaneously, so you’ll need to inspect your complete fuel system to determine the source of the problem.

It is possible that a malfunctioning EVAP canister or fuel pump is to blame for the odor of gasoline.

3. Check Engine Light

If you’re driving an older car, you’re more likely to overlook the check engine light. You may be able to ignore some warnings that appear, but the check engine light will not alert you to any new problems that may arise.

In order to keep an eye on the health of your vehicle, I propose that you either get a cheap diagnostic instrument or have your vehicle diagnosed every few months. As a result of my current car’s random problems, I run diagnostics more regularly in order to catch more serious issues before they cause any damage.

The Amazon Product Advertising API was used to get the prices displayed here.

As of the date/time stated, prices and availability of products were correct. However, prices and availability are subject to change. Please note that any price and availability information posted on [relevant Amazon Site(s)] at the time of purchase will be applied to this product’s purchase

4. Smoke Coming From The Exhaust

Exhaust pipes are long gone, with the exception of a few 2 stroke and carburetor engines still emitting white puffs of smoke. A issue with the air-fuel mixture is more than likely the cause of visible white smoke from a modern direct injection engine.

Although the EVAP system is unlikely to be the source of this problem, it is worth checking to see if the canister is in good working order before assuming otherwise.

5. Problems With Refueling

To speed up the refueling procedure, the gas station nozzle pours a big amount of fuel at once. A funnel is used to transfer liquid from one container to another by raising the funnel slightly so that trapped air may be expelled and the process is sped up.

A good seal on the fuel tank means the EVAP canister must suck all of the gas out of the tank before it can be filled with gas. Your fueling will be cut short because of an obstruction in the nozzle, which prevents the vapors from escaping. Do not try to force additional gas into the tank and instead, use what you have to get to a mechanic if this is the case.

How to Replace EVAP Canister

Symptoms Of Failing Evap Canisters-3

It’s not difficult to replace the EVAP canister at home, but there is one consideration to bear in mind. In the presence of gasoline fumes, even a single spark or metal-on-metal contact might result in an explosive reaction. This is unlikely, but I need you to undertake the task with attention and precision.

Tools you’ll need:

As of the date/time stated, prices and availability of products were correct. However, prices and availability are subject to change. Please note that any price and availability information posted on [relevant Amazon Site(s)] at the time of purchase will be applied to this product’s purchase

A $100 EVAP canister replacement labor bill is not uncommon, so purchasing your own tools makes financial sense. When it comes to fixing your automobile or even your home, almost all of the items on this list are essential.

Steps to replace the EVAP Canister:

  • Lift the back of the vehicle on jack stands to gain access to the EVAP canister.
  • Locate the EVAP canister – in terms of shape, it’s similar to the exhaust muffler.
  •  Unscrew the bolts holding the canister in place.
  • Wires need to be disconnected before the canister can be removed.
  • Take the canister out of the protective casing and compare it to the one you’ve bought.
  • If your replacement came without an evaporator, use the one attached to the old canister.
  • Put the new canister back into the protective casing.
  • Underneath the vehicle, attach the wires, then screw the casing back in place.

To learn how to remove and reinstall an EVAP canister, see this helpful video.


How much does it cost to replace a vapor canister?

The price of the EVAP canister has a significant impact on the total cost of the project. Most ordinary cars employ a $100 vapor canister for a total cost of $200-250, which is what is used in the majority of them.

Can you drive with a bad EVAP canister?

You will be able to drive your vehicle even if your EVAP canister is faulty. In any case, the odor of gasoline and the inability to meet pollution requirements are good enough reasons to have the canister changed out.

Can you clean an EVAP canister?

Compressed air can be used to clean activated charcoal, but never liquid!

If you’re going to remove the EVAP canister, you should also replace it because the efficiency of cleaning it is unknown.

Do you need a vapor canister?

Attempting to bypass or remove the vapor canister or the EVAP system may result in increased emissions, hence this should never be attempted. Removing the EVAP system is not only against the law, but it also results in the car failing emission testing.

What are the symptoms of a bad purge valve?

In contrast to EVAP canister issues, purge valve issues will be distinct from these. This might result in a harsh idle and poor performance, as well as reduced fuel efficiency. If there is a problem with the purge valve, the check engine light should come on.


You can gather the necessary tools and do the EVAP canister replacement yourself now that you are aware of the signs of a bad canister. If you do it yourself, you can save paying for an auto technician while simultaneously learning a new skill and keeping all of the tools you need for future DIY projects.