Engine Code p0101 Meaning, Causes, Fixes (5 Steps)

Has your car recently set a p0455 fault code?

If so, don’t worry. You are in the right place.

We have the information you need to remedy the root cause of your pesky check engine light.

In this PopularMechanic article you will learn:

  • What Does The p0455 Code Mean?
  • What Caused The p0455 code (Possible Symptoms)?
  • How To Diagnose An p0455 Code?

And Much More!

Engine Code p0455 Meaning, Causes, Fixes (3 Steps)

We all love to hate a check engine light! There are few things as inconvenient or aggravating as being forced to spend your day wondering if your vehicle is going to leave you stranded on the way home from work.

We know exactly how you feel, as we have been there before. That is why we have put together the following guide. 

What follows is a comprehensive guide to assist you in diagnosing and repairing the root cause of your vehicle’s p0455 trouble code. 

It is our hope that this minimizes your frustration, eases your mind, and gets you back on the road much quicker than you ever thought possible.

What Does The Code p0455  Mean?

DTC (diagnostic trouble code) p0455 is designated as “evap system large leak detected.” But what exactly does this mean?

All modern, emissions-compliant vehicles feature an evaporative emission control system. This system recycles fuel vapors back into your vehicle’s intake, as opposed to letting them escape into the atmosphere.

In the case of error code p0455, the vehicle’s management software is detecting a malfunction in this evaporative emission system, in the form of a substantial leak.

Check out this article for more on what code p0455 means.

What Caused The p0455 code (Possible Symptoms)?

A vehicle’s evaporative emission system is closed in nature. Any type of leak whatsoever will trigger an EVAP code.

In the case of p0455, the EVAP leak that has been detected is substantial. The following are some of the most common possible causes of DTC p0455.

  • Loose gas cap 
  • Defective gas cap
  • Damage fuel filler neck to gas tank
  • Structural defects to EVAP canister
  • Cracks or holes in EVAP hoses
  • Faulty or stuck EVAP purge valve
  • Faulty or stuck EVAP vent valve solenoid
  • Cracked or damaged fuel tank
  • Inaccurate pressure sensor

Since a vehicle’s evaporative system is solely emissions based, it is unlikely that you will notice any additional symptoms outside of a DTC in the event of a system leak.

However, in rare cases, the following symptoms can be observed.

  • Fuels odor radiating from rear of the vehicle
  • Slight decreases in fuel economy

Read More >> How Often Should You Change Spark Plugs?

Did you know: The evaporative emissions control system, a.k.a the EVAP system, was created to capture emissions vapors from within the vehicle and direct them into the engine where they can be burned.

How To Diagnose An p0455 Code?

  1. Check for Additional Codes
  2. Check Fuel Cap
  3. Perform Visual Inspection
  4. Perform Smoke Test
  5. Run Functional Tests

In order to rid your vehicle of its check engine light, you must first determine the root cause of your p0455 OBD-II trouble code.

Determining this underlying issue is done in a series of diagnostic steps.

Step 1: Check For Additional Codes: 

Before proceeding with the following diagnostic steps, you should always use a scan tool or OBD-II code reader to check for the presence of additional trouble codes.

These codes can assist you with your diagnosis, or alert you to additional issues.

Step 2: Check Fuel Cap: 

By far, the most common cause of a p0455 trouble code is a loose fuel cap. Begin by ensuring that your fuel cap is tight and does not appear damaged.

After doing so, clear your codes with the assistance of an OBD-II scanner, and take the vehicle for a test drive.

If the check engine light returns, replace your fuel cap, and again test drive the vehicle. 

Step 3: Perform Visual Inspection: 

If your p0455 DTC persists, you will need to perform a careful visual inspection of all EVAP system components.

This includes the fuel filler neck, fuel tank, charcoal canister, and all EVAP hoses. Additionally, pay attention to your nose.

A substantial leak will often produce a somewhat strong fuel smell.

Step 4: Perform Smoke Test: 

If you cannot spot the source of your vehicle’s EVAP system leak during your inspection, the next course of action will be to perform a smoke test.

This is done by hooking a smoke machine into the EVAP system. Once the system has been filled with smoke, any external leaks will be easily visible.

Step 5: Run Functional Tests: 

In the event that the source of your vehicle’s EVAP leak has still not been determined, it is possible that a faulty valve, solenoid, or pressure sensor is to blame for your vehicle’s p0455 fault code.

The viability of these components can often be determined through functional tests carried out through the use of a scan tool.

The extent of how these tests can be used vary from vehicle to vehicle.

Read More >> What Does The P0420 Engine Code Mean?

How Do I Fix An p0455 Code?

  1. Replace Gas Cap
  2. Replace Damaged Components
  3. Replace Defective Valve or Sensors

With a solid diagnosis made, it is time to get down to the business of repairing the issue at hand. The following steps will guide you through this repair process.

Step 1: Replace Gas Cap: 

One of the quickest and simplest ways to repair an EVAP system leak of any kind is to replace your vehicle’s gas cap. A faulty gas cap is the underlying issue in the vast majority of EVAP system leaks. 

Step 2: Replace Damaged Components: 

If damage to any EVAP system component was observed, replacement is advised. Make sure to only use quality, OEM grade components during these repairs, to avoid future problems.

Step 3: Replace Defective Valves or Sensors: 

In the event that functional testing has shown a sensor or valve to be defective, replacement will be necessary.

Read More >> What Do You Do About The Service Engine Soon Light?

P0455 Diagnosis and Repair Made Easy

As with any fault code, diagnosing and repairing the root cause of your vehicle’s p0455 DTC is seldom as difficult as one might think.

The key to success in this regard, is to have a solid plan in mind.

By following the simple steps above, you will be well on your way to banishing that annoying check engine light from your dash for good.

About Your Mechanic

About Josh Boyd

I’ve been an ASE Certified automotive/heavy equipment technician since 2010. I began my career performing basic automotive maintenance at a service center before working as a Toyota technician at my local dealership.

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