What's an EVAP leak? Are You Safe to Drive with It?

An EVAP leak could be caused by many reasons. Let's examine the meaning and cost of repairing an EVAP leak.

We determine if an EVAP leak is dangerous enough to cause it to be unsafe for you and your passengers.

What's the EVAP Function?

EVAP refers to an evaporative emissions control system. The EVAP functions to trap harmful fumes in the tank and not out into the atmosphere.

A properly functioning EVAP system will reduce air pollution to a minimum. Additionally, the crucial system ensures the odor of fuel doesn’t reach the cabin of the vehicle.

What's an EVAP leak?

Trouble codes indicating an EVAP problem indicate that there are problems with your evaporative emission controller system. There are many parts that make up this system, so it’s imperative to read the diagnostic code fully. 

It could come from the vacuum feed line, gas tank filler tube or gas cap. You might also see the leak in your vacuum control valve, charcoal canister, or vacuum pump.

Causes of EVAP leaks

Strangely enough, a very common leak cause is a gas cap that wasn’t properly secured. It usually happens after you have filled up your car. Many people head to the mechanic when the Check Engine Light comes on only to realize that the gas cap hadn’t been tightened correctly or if you didn’t shut off your car engine while you were refueling.

The gas cap should be properly sealed to prevent a bigger problem. This could indicate a problem with the O-ring seal or leakage in one of your hoses. It could also be caused by a defective purge valve or leak detector pump.

An EVAP smoke machine is the best way to locate a leak.

Symptoms for an EVAP-Leak

However, how can you determine if your EVAP is leaking?

The first sign of an EVAP problem is a fuel smell in your car. Rare cases may result in a failure to pass emission tests or poor engine performance.

Below is a detailed listing of symptoms that may be present when there's an EVAP problem.

1. Fuel Smell

The smell of fuel is one of the first signs you may have an EVAP leak. Although the gas that you inject into your car is liquid, it turns to a gas in the system and creates many fumes.

A vapor leak can cause a noxious odor if there is a small fault with the EVAP system. You won’t have any trouble recognizing the smell and will immediately know something is wrong. It’s never safe to have gasoline vapors escaping the system, which is why you want to have it checked out right away.

2. Make sure your engine light is on

Check Engine Lights are one of the signs that an EVAP leak has occurred. This is often accompanied by a fuel smell.

But, the Check Engine Light may mean many things. You can only determine whether it's a leak by running a scan of your vehicle with your diagnostic instrument.

3. Poor Engine Performance

Your engine may not run properly if there is a leak in your EVAP system. You might experience rough idle and problems with acceleration.

In order to maintain a balanced gas-air mixture, it is necessary that there is enough fuel. Combustion must occur perfectly for the engine to run right, but it can’t when there is a leak.

4. A difficult start

Air can get in the fuel system if there is a leak. The fuel/air ratio can be distorted, which could cause problems when the engine starts.

If you are having trouble getting your car started, it doesn’t automatically mean a leak. That’s why it’s vital to have a professional look at your vehicle.

5. Failure to Pass the Emissions Testing

Sometimes, drivers don’t even know there is a leak until they head to have an emissions test. A failed emissions test could indicate that your EVAP system is not working properly.

If the system can’t direct the vapors into the combustion chamber of the engine or filter them out with the tailpipe, they will leak out of the car in other ways. An excess of pollutants will cause your car to flag up during the inspection.

What is the cost to repair an EVAP leak?

The cost of repairing an EVAP leak depends on which type code you're dealing with. The cost to repair a gas cap that is broken costs only $10. However, the cost of replacing an EVAP cartridge canister will run you much higher. This canisters often run $200 to $300 just for the parts.

An OBDII scanner is the best tool to find out what's wrong. An OBDII scanner can help you find the cause of your problem and point you in the right way. You can often save money by fixing the problem yourself.

Can I Drive With an EVAP Leak?

Technically, there’s nothing stopping you from driving with an EVAP leak. However, it’s never wise to travel while gas fumes are infiltrating the cabin or the atmosphere around the car.

Check the gas cap before the Check Engine Light turns on. If that isn’t your problem, head to a professional to have the system looked at.