How to Fix P0457 Code: Repairing The Evaporative Emissions System

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a car gas cap

Do you have a P0457 code and don't know how to fix it? This blog post is for you! Many people don't know how to fix this code, but it's not that difficult. We will walk you through the process step-by-step so that you can get your car up and running again in no time.

What is Code P0457?

The P0457 code is a diagnostic trouble code related to the evaporative emissions system. The evaporative emission system is responsible for capturing and storing fuel vapors from the tank and then releasing them into the atmosphere.

This leak can cause fuel vapor to escape into the atmosphere, which is bad for both the environment and your car. When the Powertrain Control Module (PCM) detects a leak in the system, it will throw the P0457 code.

Symptoms of Code P0457

If you have this code, you will likely notice one or more of the following symptoms:

  • A "check engine" light that stays on
  • Reduced fuel efficiency
  • Poor performance
  • Smoke from the exhaust pipe

Causes of Code P0457

There are several possible causes of this code, including:

  • Missing or loose gas cap (most common)
  • Damaged vacuum hoses
  • Cracked carbon canister
  • Faulty purge valve
  • Faulty vent control valve

How to Diagnose Error Code P0457?

Another diagnosing day! If you are an avid reader of our blog post, you know that diagnosing is crucial for fixing any diagnostic trouble code issue. So, without further ado, let's get to it!

Check for Other Trouble Codes

Of course, the same goes with troubleshooting other codes; you will begin the diagnostics by checking for other trouble codes related to the P0457 code. This will help you rule out potential causes and make your diagnosis process more manageable.

Check Gas Cap

Check the fuel cap and ensure it is properly closed and sealed. A loose or faulty fuel cap can cause a decrease in a vacuum, which will then trigger the P0457 code.

Inspect the Hoses

If it is not the problem, check the vacuum hoses. These can be easily damaged, so make sure they are all connected and in good condition. These hoses can become dry-rotted over time and develop cracks, which will allow fuel vapors to escape. In that case, cases, you may need to replace the hoses.

Check EVAP System

After you have checked the fuel cap, the next step is to check the EVAP system for any leaks. However, the leaks may be too small to see with the naked eye in some cases. In this case, you need to use a smoke machine to help locate any potential leaks.

How to Fix Code P0457?

Once you have found the source of the leak, you can then fix it. This may involve replacing parts or seals within the system. If you are uncomfortable fixing yourself, you can take your vehicle to a mechanic for assistance. But if you are confident enough to do the work yourself, follow these instructions:

If the cause of the leak is a damaged or loosened gas cap, fix or replace the gas cap. If the cause of the leak is a damaged hose, replace the hose. Here's how!

Step-by-Step Guide to Replacing the Hoses

  1. Locate the hose that needs to be replaced.
  2. Cut the old hose off about an inch away from where it connects to the tank or other component.
  3. Slip the new hose over the barb and tighten it down with a wrench.
  4. Reattach any clamps or connectors, and you're done!

If the cause of the leak is a bad seal or gasket, you'll need to replace it. Here's how:

Step-by-Step Guide to Replacing the Gasket

  1. Locate the seal or gasket that needs to be replaced. This is usually where two metal parts join together.
  2. Use a sharp tool to scrape any old sealant from the surface.
  3. Apply new sealant to the surface.
  4. Reattach the parts, and you're all set!

If the leak is coming from a faulty EVAP system, you'll need to replace the entire system. Here's how:

Step-by-Step Guide to Replacing the EVAP System

  1. Locate the EVAP canister, which is usually located near the fuel tank.
  2. Detach the hoses and connectors from the canister.
  3. Remove the mounting bolts and take them out of place.
  4. Install a new canister and reattach all of the hoses and connectors.
  5. Tighten the mounting bolts to finish the job.

Common Mistakes When Diagnosing the Code P0457

When trying to fix the P0457 code, a proper diagnosis is required. However, some people make mistakes, especially when they are not knowledgeable about possible causes. Some of the most common mistakes are:

  • Not correctly diagnosing the problem
  • Trying to fix a leak that's not there
  • Replacing parts that don't need to be replaced
  • Not checking for other diagnostic trouble codes.

Code P0457 FAQs

1. Is the P0457 code serious?

Yes, it is best to consider this issue as a serious one because the P0457 can increase your vehicle's fuel emissions while decreasing your fuel economy.

2. Can I drive with the code P0457?

If the warning light is illuminated, it's not safe to drive. The P0457 can cause your vehicle to pollute more and decrease fuel economy.

3. Can this be a cause of failed emission tests?

Yes, the P0457 can cause a failed emission test because you may notice smoke in the exhaust, and the Check Engine Light will be illuminated.

4. How much does it cost to fix the code P0457?

The cost to fix the code P0457 can vary, depending on what needs to be done. If you need an EVAP system replacement, it can be $100 to $600.

5. What tool can I use to repair this error code?

When diagnosing this error code, you'll want to use a scan tool that can read emission-related codes. You'll also need essential automobile tools for components replacement.


If you find yourself with a P0457 code, don’t panic! Diagnosing and repairing the leak, which is the usual cause of this code, can be done relatively quickly if you have the right tools and knowledge.

We hope this article was able to help and guide you in fixing your P0457 trouble code. Don’t hesitate to ask in the comment section below if you have any other questions. Thanks for reading!