Evaporative Emission System (EVAP) Leak Detected – What To Do?

Evaporative Emission System (EVAP) Leak Detected: What To Do?So you're driving down the road, and everything is fine but you notice that check engine light on the dashboard. Your car is running just fine you don't know what it could be. When checking the error codes for your car, you see that there is a leak in the Evaporative Emission System. What does that mean and what should you do? We researched the topic and to bring you this guide on EVAP leaks.

The first thing that you should check is the fuel cap. This is the most common cause of leaks in the EVAP system. If you get a trouble code such as a P0456 evaporative emission system small leak detected here are some things that you should check first:

  • Missing or loose fuel cap
  • Correct fuel cap
  • EVAP canister or fuel tank leaks
  • EVAP emission system hose leaking from your fuel tank
  • Bad purge valve or vent valve for the EVAP system

So now, you have an understanding of what can cause your check engine light to come on and some areas that you can check when you determine that you have a leak in the  EVAP system, but how do you do that? We have you covered. We did the research and wrapped everything up in the one helpful article for you, so read on for our suggestions on what to do if you have an EVAP system leak.

What is An EVAP System?

This is an excellent question because most people are not aware of what the EVAP system does in a vehicle.

The EVAP system is a canister that contains charcoal that traps unburnt fuel-air fumes from your gas tank. The fumes are then circulated back through allowing them to be burnt in the combustion engine. The system also helps balance the fuel-air mixture being drawn into the engine.

Where is The EVAP Canister Located

The EVAP canister is located to the rear of the muffler on either side. It is usually located above the muffler.

Is An EVAP Leak Serious?

The answer to this question really depends upon where is the leak is in the EVAP system. If it is a leak in the gas cap, then it's probably not going to be too dangerous or expensive to fix. Have a hole in your fuel tank that is allowing air to enter the system; it may be a little more costly to fix as well as a rather tricky repair.

Is It Okay To Drive With An EVAP Leak?

The answer to this question ties into the paragraph above. Depending upon where the leak in the EVAP system is occurring, you may be able to drive for a little while without having to have too much concern about the EVAP system other than the check engine light is on. It is always a good idea to try and take care of whatever issue is impacting the vehicle and turning the check engine light on as soon as possible.

Can A Car Run Without An EVAP Canister?

A vehicle can technically run without an EVAP canister; however, it is not suggested. The EVAP system helps to remove the unburnt fuel-air fumes from your fuel tank and routes that mixture safely through hoses so that it can be burnt during the standard combustion process.

There may also be a caveat to this if you live in an area that does not have emission controls you may be able to remove the canister completely in the event of a problem. This is easily done if you have some mechanical knowledge. If you do not you can seek the help of a professional. You will want to purchase and install another canister as soon as you can as it does perform an important function.

Can An EVAP Leak Cause A Misfire?

Because it is tied to the fuel-air mixture of a vehicle, an EVAP leak can cause a misfire. This is typically going to be related to holes in the hoses and also where the leak into the system is occurring — making any adjustments to the fuel-air mixture or the explosive properties of the fuel-air mix going into the engine and can always cause problems with misfiring.

How Much Does It Cost To Fix A Leak In The EVAP System?

The answer to this question is going to depend upon the location of the leak and the portion of the system that is being affected by that leak. For instance, a leaky gas cap is a cost-effective fix they can range anywhere between $3 and $55. The leak is coming from a hole in the gas tank, and that, on the other hand, can cost anywhere between 50 and $450 for parts and labor.

How Do You Fix A Small EVAP Leak?

If the leak is coming from the gas cap, it just may require the gas cap being appropriately tightened down after filling.

After the leak is occurring in a hose that is coming from either the fuel tank or the EVAP canister, then it should be relatively easy to remove the hose and replace it. Small holes in the fuel tank can frequently also be repaired with products such as J-B Weld or other products available on the market. It is essential to remember that these repairs are typically going to be temporary in nature, and you will not want to rely on them long-term.

Will An EVAP Code Clear Itself?

The EVAP code may clear itself after the vehicle is driven fifty to a hundred miles after the problem has been repaired. Before doing or attempting any heavy-duty repair work, you should check the easy stuff.

Start with making sure that you are gas cap is appropriately tightened down and make sure that there is no gasoline but is leaking from the fuel tank of the vehicle. Having the valves on the EVAP system checked requires some mechanical ability and the appropriate tools.

It is also important to remember that after repairs are completed on the vehicle, it may need to be driven for some time for the system to recalibrate itself to confirm with the vehicle's computer that the problem has been resolved.

Is The EVAP System Covered Under Warranty?

The EVAP system of the vehicle is typically associated with the drivetrain, so if you have a new car that has a warranty on the drivetrain, problems with the EVAP system should be covered under warranty. A used vehicle is not going to have that luxury unless you have had mechanical work done on the EVAP system and it may be covered under that warranty.

There is not an industry-standard warranty that applies specifically to the EVAP system, although it is worth noting that if you have a newer vehicle and you are having trouble with the EVAP system, you may want to check and see if there have been any recalls issued on that vehicle. This is always a good thing to do when you're looking at any repair that might be super costly.

Vehicle Age Matters

Newer vehicles often have less of a chance of there being issues with the EVAP system as everything is brand new. There should be no broken hoses or holes in the fuel tank unless you've given the vehicle rough or possibly had a collision.

A large number of the hoses on vehicles are made out of rubber and as rubber gets older it tends to become dry and brittle so if you have an older vehicle and it's always a good idea to check the hoses if you are unable to spot where the problem may be coming from you should have a professional diagnosis.

Replace The Fuel Cap

Most people don't realize this, but there is a rubber fitting over most fuel tanks that the gas cap inserts into. Over time this seal can break or deteriorate to the point where excess air is getting into the system. The seals are easily replaced, and fuel caps are also easily replaced.

It is always a good idea to make sure that you are purchasing the correct fuel cap for your vehicle if you are replacing the original. Not all of these are Universal, and your vehicle may require a specified fuel cap.

Identify the Smell

There's a problem with your EVAP system; you may notice a robust fuel-air odor coming from under the hood of your vehicle. This will be much different from the smell of exhaust as the fumes from the gasoline will be rather potent; it will smell very similar to gas that is coming freshly out of the pump. If you have a situation such as this, the repairs must be conducted immediately as unspent fuel pouring into the engine compartment of your car can result in explosion fire and death.

Now that you have an idea of what the EVAP system does in your vehicle, and what to look for, fixing this code should be fairly easy. The hardest part is oftentimes having the codes read so that you can know where to start. When dealing with leaks in the system always be careful to conduct repairs safely. In most cases, these repairs do not need to be corrected immediately.

If there is fuel leaking from the gas tank you should have the vehicle safely towed home or to a shop, exhaust systems are very hot and fuel can ignite if it drips on to hot pipes.

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