P0455 – Evaporative Emission System Leak Detected (large leak)

Leaks in your evaporative emission control system can cause a lot of problems. In the short-term, they reduce your fuel economy. Left unchecked, they can contribute to deeper engine issues that could require costly repairs.

The P0455 OBD2 code is one of the first warning signs that there are leaks and other problems with your EVAP system. However, it can be a tricky code to diagnose correctly since various systems can cause it. Read on to learn how to find the cause of P0455 best and what you need to do to fix it.

P0455 OBD2 Code Definition

  • P0455 Code (Generic): Evaporative emission control system leak detected (no purge flow or large leak)
  • P0455 Chrysler: Evap System Large Leak
  • P0455 Ford: (EVAP) System Leak Detected (gross leak/no flow)
  • P0455 GMC: Evaporative Emission (EVAP) System Large Leak Detected
  • P0455 Nissan: (EVAP) System Leak Detected (gross leak/no flow)
  • P0455 Chevy: EVAP System Gross Leak (0.080″) Detected
  • P0455 Jeep: Evap System Large Leak
  • P0455 Dodge: EVAP Large Leak Detected
  • P0455 Hyundai: “Secondary air injection system, switching valve fault: Last occurrence – signal fault.”
  • P0455 Mercedes: A Gross Leak In The Evaporative Emission Control System Was Detected.
Here's where you can get a thorough understanding of the P0455 OBD2 code
If you want to learn about the P0455 OBD2 code, this is the right place

What Does P0455 Mean?

This code is related to the evaporative emission control system (EVAP system, for short). The EVAP system absorbs harmful components in the fuel vapors in charcoal pellets. Eliminating these components from your exhaust prevents pollutants from entering the atmosphere. From a practical standpoint, it’s also key to passing a state emission test.

There are two valves on the EVAP system: the vent control valve, which lets air into the canister, and the purge valve, which releases the cleaned air. Both these valves stay open when the engine is running. The engine control module (ECM) will occasionally close them to test for leaks, however. If the system doesn’t maintain proper pressure during this test, the P0455 code is triggered.

This code typically indicates a large leak. While this can occur at multiple points of your system, it is often in the vapor recovery system, not a fuel leak.

What Are The Symptoms Of The P0455 Code?

There are not usually any drivability issues associated with the P0455 trouble code. You may notice a few symptoms, though, including:

  • Activation of the check engine light
  • Smell of gasoline around the tank
  • Reduced fuel economy

What Are The Causes Of P0455?

There are several problem can lead to P0455 code, but loosing or damaged gas cap is the most common.
Loosing or damaged gas cap is the most common cause of the P0455 trouble code
  • Gas cap. The most common cause of the P0455 trouble code is a loose or damaged gas cap. Damage to the filler neck could also be preventing the cap from sealing properly.
  • EVAP hoses. Leaks and damage in the hoses of the EVAP system are another common cause of code P0455. Hoses can crack with age or be jostled loose by engine movement.
  • EVAP system valves. Both the vent control valve and purge valve can stick or fail and trigger this code.
  • Charcoal canister. The canister and its surrounding pipes can clog. This code will also activate if the cylinder is damaged or cracked.

How Serious Is The P0455 Code?

Usually, this code is not very serious. You can safely drive your vehicle while you prepare to make repairs. However, if there is a strong fuel odor, you should repair your car as quickly as possible.

How To Diagnose The P0455 Code

Tools you’ll need:

OBD2 scan tool is one of the most important tools that you need to diagnose P0455 code
An OBD2 scanner will help you scan for ohter trouble codes, and also P0455 code.
  1. Scan for other trouble codes. If any others come up, address those first.
  2. Visually inspect your gas cap for cracks or damage. Examine the filler neck as you do to check for leaks and damage. If the gas cap is loose, tighten it, clear the codes, and scan your car again.
  3. Check the hoses around your EVAP system for damage. Re-connect any that have come loose and replace any that are damaged.
  4. Use a multimeter to test the vent control valve and purge valve to ensure they’re receiving power. If they’re not, the issue may be with the wiring or the valve itself.
  5. Apply a vacuum to the EVAP system using a vacuum pump. If the vacuum holds, the valves are good. If the valve opens, either the valve or the solenoid have failed.
  6. Conduct a smoke test on your EVAP system to check for leaks. If none are found, the problem is likely with your charcoal canister or engine control module.

Common Mistakes To Avoid While Diagnosing The P0455 Code

Pay attention to other codes that come up along with P0455. If you see P0440 or P0456, this tells you the problem is a solenoid failure or a system leak. Keeping an eye out for other trouble codes can save you a lot of time in your diagnosis.

What Should You Do To Fix The Code P0455?

Because this code can be triggered by various systems, identifying the root cause can be difficult. The best tactic is to start with the easiest and cheapest potential fixes based on your diagnosis. After each repair, clear the trouble codes and rescan your vehicle to see if the code has been resolved.

  1. Replace your gas cap, even if you don’t notice any damage. They can develop damage that’s not visible to the naked eye. This inexpensive fix could prevent you from exerting a lot of wasted effort.
  2. Repair any leaks found during the smoke test and ensure all EVAP hoses are firmly secured.
  3. Replace your vent control valve or purge valve if they failed the tests in steps 4 and 5 of the diagnosis.
  4. Clean the charcoal canister using compressed air. To do this, remove the canister from your vehicle and place it on a flat surface. Prime the air compressor by building the pressure to 50 psi then shutting it off. Attach the nozzle to the vent control valve pipe on the charcoal canister and cover the other openings with your fingers. Blow the compressed air into the canister for 1-2 minutes, then replace the charcoal canister and test the EVAP system. If it still fails, replace the charcoal canister.

In the rare instance none of these fixes clear the code, you may have a more serious problem with your engine and should take your car in for repairs.

A video about the error code P0455 explained

Tips To Avoid P0455 In The Future

Preventative maintenance can help you avoid problems with your EVAP system. Try these steps:

  • Ensure your gas cap is tightly replaced any time you remove it
  • Use a rust prevention treatment on your system to prevent corrosion (and the leaks it causes)
  • Periodically check hoses for damage

Read more: P0013 Code: Meaning, Symptoms, Causes, Diagnostics, and Fixes