P0455 Code – What It Means and How To Fix It

If the check engine light is on and you see a P0455 code on your scanner, there are a few possible reasons. We'll help you figure out what's causing this.

P0455 Code

What do you do when the Check Engine Light comes on? The best thing to do is read the codes with your OBD-II compatible scanner. If the scanner reveals the P0445 code, you may be more confused than you were to begin with. 

To end your confusion, I’ve put together this handy guide revealing the meaning, symptoms, and causes of the P0455 trouble code. Plus, I show you how to diagnose the problem and repair it. 

Code P0455 Definition

P0455 – Evaporative Emission Control System (EVAP) Large Leak Detected

What Does the P0455 Code Mean?

The P0455 trouble code is a generic powertrain code, but not all manufacturers use it. This DTC indicates that there’s a significant leak in the EVAP system. It’s been reported with many brands, such as Chevrolet, Nissan, Jeep, Ford, and Dodge.

I recommend double-checking what this code means according to your manufacturer. In some rare cases, it may have nothing to do with the EVAP system. 

When it does have to do with the EVAP system, it’s the more serious version of trouble code P0442. Both of these have to do with the evaporative emission control (EVAP) system. The purpose of this system is to prevent fuel vapors from escaping into the environment. 

What Are The Symptoms Of P0455?

When there’s a leak in the EVAP system, you probably won’t notice any strange symptoms. Aside from the Check Engine Light, you might not have known that anything was wrong.

While no driveability issues should occur, you may notice these problems.

  • Check Engine Light
  • Slight fuel smell
  • Failed emissions test

What Are The Causes of P0455?

The P0455 trouble code is caused by anything that would lead to a leak in the evaporative emission control (EVAP) system. Most often, one of these problems is the culprit. 

How Serious is the P0455 Code?

Low – An EVAP leak isn’t normally a big deal because it won’t lead to driveability concerns. If you can’t have it fixed right away, you may be okay to wait for a short time. With that said, there are some problems, such as a defective gas tank, that would lead to more alarm. If fuel were leaking out of the tank, you would be at risk.

Additionally, you don’t want to leave the problem unfixed for too long. The emissions are higher than they should be, and the car could fail a mandatory test. 

Open Car Gas Cap

How Do I Fix the P0455 Code?

Once you figure out what is causing the problems, you are ready to fix it. Only a thorough diagnostic evaluation is going to tell you what to do next. 

However, here are a few of the most common fixes.

  • Tighten or Swap out the fuel cap
  • Repair broken EVAP system line
  • Replace purge valve
  • Replace charcoal canister
  • Replace fuel tank
  • Replace vent valve
  • Replace leak detection pump
  • Replace FTP sensor

Common P0455 Diagnosis Mistakes

The easiest mistake you can make is to overlook the obvious. Because you are so focused on the EVAP system leaking, you could miss the simple problem of having a defective gas cap. 

This is less common with this trouble code than with a minor leak, but it’s still possible. For this reason, I always recommend walking through all of the diagnostic steps to find the source of the fault. 

It’s also possible that you forgot to tighten the gas cap properly, or that you let your vehicle run while refueling, which could cause the P0455 code to appear. In this case, it will be enough to clear the codes to solve the issue.

Evap Purge Control Valve
EVAP purge control valve

How to Diagnose the P0455 Trouble Code?

Speaking of diagnostics, the steps to handle the P0455 code are simple. First, you always want to read your service manual because every system operates differently. If our directions contradict what you read in the service manual, you should follow the advice from the manufacturer.

Otherwise, here are some basic steps to follow.

  1. Check the engine codes with your compatible scanner. If you get more than the P0455 trouble code, it might help you determine what’s going on. 
  2. Examine the gas cap. Tighten up the cap if it is loose. Otherwise, if you notice any damage – no matter how small it appears – you should replace the gas cap. This is one of the cheapest repairs you can make, so it’s worth trying.
  3. Look at the EVAP hoses that attach to the air box. If they have come disconnected or are damaged, it’s time to fix them. 
  4. Look for any damage to the fuel tank. If there’s any fuel leaking, you need to repair this problem ASAP.
  5. Examine the charcoal canister for cracks or damage. Replace it if it’s worn.
  6. Inspect the purge volume control valve. These are known for becoming sticky, which causes a leak. You can use your compatible scanner to open and close the purge control valve, if it won’t open or close properly, you need to replace it.
  7. The same goes for the vent control. You need to check to see if it’s leaking and causing problems.
  8. Run a smoke test with an EVAP smoke machine to see if you can find the leak.
  9. Check with the manufacturer to see if service bulletins have been released. If there are known problems with the EVAP system, the automaker will instruct how to fix them. 

You may not feel equipped to handle this problem. If so, don’t be afraid to reach out to your local mechanic. Sometimes, it’s better to trust someone else with these issues, especially if you don’t know a lot about the EVAP system. 

How Much Does It Cost To Fix Code P0455?

Depending on what you find during your diagnostic check, you may discover that one of these repairs is needed. I’ve estimated what you might spend on parts and labor. Keep in mind that it could be cheaper if you perform the repairs on your own. 

  • Replace fuel cap – $10-$50
  • Repair EVAP line or hose – $15-$600
  • Replace purge valve – $100-$350
  • Put in new charcoal canister – $150-$600
  • Swap out fuel tank – $750-$1,500
  • Replace vent valve – $100-$350
  • Install new FTP sensor – $250-$500
  • Put in new leak detection pump – $150-$450

A Mechanic’s Tips About The P0455 Code

It’s important to evaluate all trouble codes in a bunch. The P0455 code by itself isn’t going to tell you much. For that reason, you must look at the bigger picture.

When you run your compatible code scanner, take note of any codes that have to do with the EVAP system. You can use these like puzzle pieces to narrow down what area of the system might be to blame. 

If there are too many codes to make sense of, reset them and take a test drive. Once the Check Engine Light comes back on, you can read all of the new codes that are set and figure out what’s going on. 

Is code P0455 serious?

Most of the time, the P0455 code is not serious. If the EVAP system has a leak, it won’t cause any driveability issues. For the most part, it’s probably just leaking more emissions into the atmosphere, which isn’t good. That’s why you still want to have it checked as soon as you can. 

Can a gas cap cause a P0455 code?

Yes. A loose or defective gas cap can cause the P0455 code to set. This is the easiest fix, allowing you to either tighten the cap or purchase a new one. Most gas caps don’t cost much more than $10, so the fix won’t break the bank either. 

How do I fix error code P0455?

First, you want to run through a diagnostic check to see what’s causing the problem. Once you know the part that’s defective, you can replace it. The problem could be something as small as a loose gas cap, or it could be something major, such as a leak in the fuel tank. 

How serious is an EVAP leak?

Most EVAP leaks are not major. Because the system is so sophisticated, there are numerous parts that can fail and lead to a leak. With some diagnostic work, you can pinpoint where the problem is and fix it quickly. The only time you would need to worry is if the leak is in the fuel tank. 

Conclusion

Even if you immediately get worried about the P0455 code, there’s probably nothing major to be troubled about. In fact, the problem could be as simple as having a loose gas cap, which only takes seconds to repair. While it’s important to figure out what’s wrong and fix it, this trouble code isn’t nearly as concerning as many others.

Still, I never recommend continuing to drive with the Check Engine Light on. It’s your responsibility to take care of your car and the environment around you, so it’s important to have it repaired as soon as you can. Not only that but the longer you drive with the light on the dashboard, the more chance you have of missing something important happening with the car. It can’t alert you that something’s wrong if the alert is already on and being ignored. 

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