How to Fix Code P0455: Tips for Car Owners

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What do you do if your Check Engine light comes on when driving? Just relax, pull out your OBD scanner, and see what error code is triggered. If it's a P0455 error code, don’t worry! We'll help you fix this.

This blog post will discuss the possible causes, symptoms, and fixes for the P0455 trouble code. Read on!

What is Code P0455?

The P0455 is a diagnostic trouble code (DTC) that stands for "Evaporative Emission Control System (EVAP) Large Leak Detected." A car’s operating system will detect a significant leak within the evaporative emission system, which causes fuel vapors to escape into the atmosphere.

Newer vehicles use an integrated evaporative emission system to control the release of fuel vapors. This system contains several components, including a canister filled with charcoal, a purge valve, and a vent valve. The canister stores the fuel vapors until the engine can burn them off. 

While the purge valve allows fresh air into the canister to draw out and burn off the vapors, the vent valve prevents fuel vapors from escaping into the atmosphere. If any of these components are not working correctly, it can set off the P0455 code.

The code P0455 is also set when the Engine Control Module (ECM) detects leaks within the EVAP system, making it impossible to capture and retain fuel vapors. This leak is registered by abnormal readings captured by an onboard pressure sensor and interpreted by the vehicle's ECM.

When discrepancies in these pressure readings develop, an active fault code is stored, and a vehicle's check engine light is illuminated.

Symptoms of Code P0455

Before your check engine light is illuminated on your dashboard, you might have been experiencing drivability issues with your vehicle. Aside from those, you may also experience these symptoms:

  • Strong fuel smell
  • Poor fuel economy

Causes of Code P0455

When diagnosing the P0455 code, knowing all the possible causes is essential. This ensures that everything will be appropriately checked and fixed. The causes of this code include:

  • A loose or missing gas cap
  • Bad evaporative emissions (EVAP) system purge valve
  • Damaged or defective canister
  • Charcoal canister leak
  • Damaged fuel tank
  • Faulty pressure sensor
  • Leak in the EVAP

How to Diagnose Error Code P0455

With all the causes mentioned above, the code P0455 may seem like a daunting problem to fix. But don't worry, we've got you covered. Here are some tips on how you can diagnose the code:

Inspect the Gas Cap

  1. Before you start, don't forget to scan for additional trouble codes using an OBD scanner. This will help           you rule out other potential causes.
  2. Check the fuel cap first. If it's not tightened correctly, this can cause a vacuum leak and trigger the P0455        code. If the gas cap is the problem, replace it.
  3. If the gas cap isn't the problem, look at any cracks or holes in this pipe that can cause a vacuum leak.

Inspect your Entire EVAP System

  1. Perform electrical testing of the purge and vent control valves for proper operation. 
  2. Inspect hoses, EVAP canister, and filler neck. Perform a thorough inspection of these components. If you        find any damage, repair or replace it.
  3. If you didn't find any problem with the components mentioned in the number 4 step, perform a smoke           test. This will help you find any leaks in the system.
  4. Once you've found and fixed the leak, reset the code and test drive your car to see if the light goes off. If         it does, then you're good to go! However, if the code P0445 persists, it could be a faulty purge valve or             solenoid.
  5. Check the EVAP solenoid wirings and function as well.
  6. Check the fuel vent line if adequately sealed. If you notice leaks, you can use an EVAP smoke machine to         put smoke into it to find the leak quickly.
  7. If everything is sealed and the solenoid works, you can now remove the trouble codes and test the car.

How to Fix Code P0445

There are many fixes for this issue, and the best option will depend on the cause. Some fixes are not as easy as we believe, so you can have them repaired by a professional if you are not mechanically inclined. However, if you can do it yourself, try the fixes below.

  • Replacing the faulty gas cap
  • Fixing the EVAP system
  • Repacing the EVAP Hoses
  • Repacing the charcoal canister

Step-by-Step Gude to Fixing the Gas Cap

The obvious fix for a loose or missing gas cap is to check the gas cap and make sure it's on tight. If it's old or damaged, you might need to replace it. So how do you do it?

  1. Start by parking your car on a level surface and opening the gas tank.
  2. Unscrew the old gas cap (counterclockwise) and discard it.
  3. Screw on the new gas cap (clockwise) until it's tight.
  4. Start the car and check to see if the code is gone.

Step-by-Step Guide to Fixing the Leaking EVAP System

If there's a leak in the EVAP system, you can use a sealant specifically designed for car leaks to fix it. However, it's not as simple as sealing and forgetting about it. So how do you start?

  1. To begin, ensure to park your car on a level surface and open the gas tank.
  2. Find the leak in the EVAP system.
  3. Clean the area around the leak with brake cleaner or a similar product.
  4. Spray the sealant around the circumference of the leak.
  5. Wait for the sealant to dry (following package instructions).
  6. Start your car and check to see if the code is gone.

Step-by-Step Guide to Replacing the EVAP Hoses

Another common fix for the P0445 code is the EVP hose replacement. The hoses are susceptible to cracking and splitting, which can cause a leak. This is a fairly easy fix.

  1. The first step is to remove the gas cap and relieve the pressure in the system.
  2. Detach the electrical connector from the EVAP solenoid valve.
  3. Unplug the vacuum line from the EVAP solenoid valve.
  4. Remove the two bolts that hold the EVAP canister in place.
  5. Carefully lower the canister and set it aside.
  6. Detach the hoses from the EVAP canister and remove them from the car.
  7. Install the new hoses, making sure to attach them securely.
  8. Reinstall the EVAP canister, making sure to tighten the bolts securely.
  9. Reconnect the electrical connector and vacuum line.
  10. Close the gas cap and start the car.
  11. The engine should run for a few minutes to pressurize the new hoses.

Step-by-Step Guide to Replacing the Charcoal Canister

A damaged charcoal canister is another cause that's triggering the code p0445. Here's how you can replace it:

  1. Disconnect the negative battery cable.
  2. Drain the fuel tank and remove it from the car.
  3. Remove the EVAP canister and the hoses and brackets holding it in place.
  4. Install the new EVAP canister and attach all of the hoses and brackets.
  5. Reinstall the fuel tank.
  6. Connect the negative battery cable.
  7. Start the car and check for leaks.

Step-by-Step Guide to Replacing the Fuel Tank

In modern cars, fuel tank leaks are one of the most frequent causes of gasoline leaks due to use and aging. So make sure to replace it if. Here's the step-by-step guide on how to do it:

Tools You'll Need:

  • New fuel tank
  • Fuel line disconnect tool
  • Ratchet and socket set
  • Wrench set


  1. Before you begin, make sure to relieve the fuel system pressure.
  2. Then, disconnect the negative battery cable.
  3. After that, drain the fuel tank and remove the fuel pump and sender using the fuel line disconnect tool.
  4. Next, remove the straps that hold the tank and take it out.
  5. Install the new fuel tank and reconnect all the lines and screws.
  6. Reinstall the fuel pump and sender unit, routing the hoses correctly.
  7. Refill the fuel tank
  8. Reconnect the negative battery cable and start the car to check for leaks. If there are no leaks, you're               done!

Common Mistakes When Diagnosing the Code P0445

No matter how easy or difficult the repair might be, some mistakes can easily be made when diagnosing code P0445.

  • One common mistake is thinking that the problem is with the EVAP system when it's a symptom of another issue.
  • Another mistake is not thoroughly checking all of the possible causes of the code before beginning repairs.
  • Spraying the sealant around the circumference of the leak without cleaning the surface.

Code P0445 FAQs

1. Is the P0445 code serious?

The P0445 code is considered a severe code and should be addressed soon. Because of its location, the code can indicate a serious problem with the emission control system.

2. Can I drive my vehicle with a P0455 trouble code and illuminated CEL?

You may drive your vehicle while trouble code P0455 as long as the gas vapor odors are not strong and no obvious fuel (liquid) leaks.

3. Is there anything I can do to prevent the code from returning?

You can do a few things to help prevent the code from coming back. Keep your engine well-maintained and ensure all your emissions control system components are working correctly.

4. Are there any long-term effects of not fixing this code?

If you don't fix this code, it could lead to more severe problems with your vehicle's emission control system. Having a strong fuel smell coming from your car is also a sign that you should get this fixed as soon as possible.

5. How much does it cost to repair this error code?

The cost can vary depending on the mechanic you go to and the severity of the problem. However, the ideal cost range between $150 to $200.


If you're experiencing symptoms or causes listed above, get your car fixed ASAP. This will save you money and keep your vehicle running smoothly. Please check out our other blog posts for more information on fixing other diagnostic trouble codes. Thanks for reading!