When you buy an automobile, you quickly learn how it operates and functions. You adjust to the noises it makes. You become attuned to the way it performs. One tiny change – a noise or a smell – will alert you to a potential problem, and give you ample time to have it fixed before the issue escalates.
Luckily, with today’s modern vehicles, it’s not just about relying on your sense of smell or hearing to detect a potential problem. Technology is now integrated into every vehicle, being the internal sight and sound that watches over everything that happens every time you start your car. Every system is calibrated to acceptable levels, and if anything moves beyond those measures, it alerts you with a tiny dashboard light.
The check engine light is one that alerts you to a variety of potential problems. Some can involve minor fixes. Some can be massive system failures – especially if you don’t fix the situation quickly.
An EVAP leak is one of those potential problems that impacts your check engine light. What is it and how do you fix it?
What is an EVAP leak?
An EVAP leak is a problem somewhere in the evaporative emission control system (EVAP). The EVAPs purpose is to contain any fumes released from gasoline, and prevent them from seeping out and impacting the environment.
The EVAP system is an important part of your vehicle’s pollution control feature, but it also serves another function: it keeps dangerous fumes from entering the cabin of your car.
How does the EVAP system work?
A vehicle’s EVAP system controls fuel vapors from escaping the fuel tank as your car sits and runs. These vapors are collected and condensed before being returned into the fuel tank. The fuel tank is a sealed system that is vacuum controlled and has purge control solenoids for the process.
As the engine runs, a vacuum is used to draw fumes into a charcoal canister where vapors are collected and condensed. As you turn the key, the engine activates a control valve which releases this vacuum into the system. The purge solenoid moves into operation and helps control the vapors, moving them back into the fuel tank.
The fuel tank has a pressure sensor to monitor this supply cycle and ensure it’s working correctly. It’s a continual process, keeping you safe while you drive, but also ensuring your car remains safe as it sits, unused.
What can go wrong with the EVAP system?
When any part of the EVAP system is compromised, it can cause a problem inside the vehicle. If a problem arises with the vacuum, solenoid, or sensor at any time, it will deliver a code to the main computer memory, alerting it to a problem within the system. It illuminates the check engine light to warn you of a potential problem.
Potential problems can include:
- Gas cap failure – this is one of the most popular shortcomings, due to regular usage
- Gas cap O ring is damaged
- Gas tank filler tube is damaged
- Vacuum feed line leaks
- Vacuum control valve leaks
- Vapor tube from the charcoal canister to the tank is damaged
- The charcoal canister is leaking
Is it safe to drive with an EVAP leak?
While it isn’t dangerous to drive with an EVAP leak, there are several reasons why you shouldn’t.
First, it is potentially harmful to the environment. Every time you drive, your car emits exhaust fumes that contribute to the destruction of the ozone. Without the EVAP fully working, you’re emitting various levels of harmful chemicals into the world.
It also impacts your drive. While you might be able to drive your car with EVAP problems for a while, eventually, you’ll have to undergo an emissions test to update your vehicle registration. An EVAP leak will prevent you from passing this test. The longer you wait to fix the problem, the more potential damage may be done.
Finally, while the EVAP is a closed system, and won’t directly impact your health if there’s a leak in the system, it can impact other comforts of driving your car. A leak can impact the pressure in your gas tank, which can affect your mileage. It’s also something to pay attention to if you park in a closed environment.
Can you pass smog with an EVAP leak?
The short answer is: maybe. It depends on the source of the problem.
In some cases, this may be the first sign you have a problem. A negative test alerts you to the fact your car isn’t working properly.
If you do notice a check engine light before an emissions test, scheduling a maintenance visit to ensure every system on your vehicle is fully operational will help keep your car in good working condition all throughout the year.
Does EVAP system affect performance?
The EVAP charcoal canister valve – the purge solenoid – acts as a switch to move vapor into the engine. If this fails, one of the first symptoms you may notice is a rough ride. You will notice your car running inconsistently when you come to a stop, or while you’re driving at low speeds. If it sticks open, it can create a vacuum leak that impacts your idle speed. If damage to the solenoid continues, it can also lead to your engine stalling out completely.
The EVAP controls vapor. A leak within the system can impact how well your vehicle starts and stays running. Any issue with interrupted internal combustion may cause your engine to stall or refuse to start altogether.
How do you fix evaporative emission system leak detected?
One of the easiest fixes is simply to replace the gas cap. Since broken seals and a loose fit can impact how much emissions are escaping, Inspect the O ring. Because the gas cap is removed continuously when you fill up, it can stretch and loosen over time.
It may also be the vacuum feed line. This line feeds from the engine intake manifold to the EVAP system control valve. Engine heat and vibration can loosen connections or even deteriorate the rubber over time.
The main component is the charcoal canister. While it’s not something that deteriorates with regularity, it can need replacing if you’re having emissions problems.
Every system on your vehicle works to keep your car running smoothly.
Whether you have a check engine light that won’t turn off, or are noticing your car is running rougher than before, don’t wait for bigger problems to arise.
Drive in today and let us have a look.
It can be the difference between a minor repair and a major overhaul.
We’ll get you back on the road in no time.