P0455 – Meaning, Causes, Symptoms, & Fixes

Code P0455 Definition

System gross leak evaporative system malfunction

Code P0455 Meaning

The evaporative emission control (EVAP) system prevents fuel vapors from escaping into the atmosphere. The fuel vapors from the fuel tank are absorbed and stored by charcoal pellets in the charcoal canister. The vent control valve is controlled by the engine control module (ECM) and allows air to flow into the charcoal canister to purge the gas vapors into the engine air intake to be burned. The flow of the gas vapors from the charcoal canister to the engine air intake is controlled by a purge valve. Both the vent control valve and the purge valve are usually open when the engine is at normal operating temperature. However, the ECM occasionally performs leak tests to ensure the evaporative emission control system is working properly. During the leak test, the ECM closes the vent control valve and purge valve to create a vacuum. If the EVAP system does not maintain the pressure, the ECM recognizes an evaporative emission control leak. In the case of P0455, it is a very large leak. This is usually indicative of a loose, broken, or missing gas cap.


  • Check Engine Light is on
  • Decreased fuel economy
  • Fuel smell


  • Loose or damaged gas cap (*Most Common)
  • Faulty or stuck vent control valve
  • Faulty or stuck purge valve
  • Cracked or disconnected EVAP hose
  • Cracked or damaged charcoal canister

Code P0455 Severity – Low    

If the fuel odor is very strong and it is apparent that there are leaks, take your vehicle to your repair shop as soon as possible. The most common problems with code P0455 is a loose gas cap or leak in the airbox hose. The system leakage can cause an excessive amount of fuel consumption if not taken care of shortly after.

Code P0455 Common Diagnosis Mistakes

Many people fail to follow the full diagnostic test and can underpay or even overpay for their solution. Fuel caps ($) are the easy fix with a run to your local auto repair shop, but people sometimes neglect the possibility of  other components it might possibly be which are more costly ($$).

Code P0455 Diagnosis Steps

Tools Needed to Diagnose:

How To Diagnosis 

  1. Scan your vehicle to verify P0455 is the only code present. If other codes are present, they must be addressed first.
    1. If you have code P0440 or code P0456, the cause of the codes is most likely a solenoid failure, or a more complex system leak. These issues must be addressed first.
  2. Check your gas cap to check if it is loose or damaged
    1. If your gas cap is loose, tighten it and clear the code.
    2. Inspect your gas cap for physical damage or deterioration. However, it should be noted that damage to the gas cap or deterioration of its components are not always noticeable. If your gas cap was not loose and you do not see any indications of failure, try replacing the gas cap anyways and clearing the codes. Gas caps are relatively inexpensive and are usually the fix for code P0455.
  3. Check for cracked or disconnected EVAP hoses near or connected to engine air box
    1. Replace cracked/disconnected hoses
    2. Clear code*


*If code returns, you will need to be given further diagnostics at a mechanic. More diagnostic steps could require electrical testing of the purge and vent control valves for proper operation. It may also require a smoke machine test to detect and find a leak in the system.

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Comments 25


June 25, 2018

Where is the vent Ctrl. Valve, purge valve, charcoal canister & engine air box located in the engine?

FIXD Marketing

June 25, 2018

Hi Eddie,

The location of the control valve, purge valve, charcoal canister, and engine air box will be dependent on your vehicle. Look in your car’s service manual to locate these.

Concerned consumer

August 5, 2018

Check your fluid levels


December 8, 2018

Fluid levels have nothibg to dp witg the evap leak. If it aint the gas cap check the fuel filler neck. Often a mechanic will vurn baby oil and spray that into the fuel lines and evap limes for around one hundred dollars. Fuel filler neck from gas cap to gas tank usually has an evap line as the evap system includes those holes on the side of where the gas station nozzle goes. Those holes go to a single tube that captures the evaporated gas and there is usually a third tube on the fuel filler neck assembly to let air into the system through a filter. The fuel filler is the part that goes from the gas cap to the tank. I patched a hole in my fuel filler neck with an epoxy stick from Home Depot in the plumbing aisle for about 4 dollars after i sanded the fuel filler with a wire brush wheel on a drill.


June 30, 2018

I got no Fuel smell But Check Engine light is on amd that Code given

FIXD Marketing

July 9, 2018

Hello Michael,

You may have damaged or cracked EVAP hoses, so you may need to run tests to pinpoint the exact problem with trouble code P0445.

The FIXD Team


July 22, 2018

I’ve been having this issue all month. My check engine light came on in June. I was told it could be the gas cap needed replacing or my fuel tank pressure sensor. I bought a new gas cap first since that was the easiest solution, but it didn’t solve the problem. So, then I had the fuel tank pressure sensor changed. The mechanics reset the codes but the check engine light came back on 2 days later with new error codes and a new problem. The dashboard was saying “engine power is reduced” and the error codes were for an accelerator pedal sensor and purge solenoid. So, I just changed both of those parts on Thursday and the check engine light went off again. Today, it came back on with this same p0455 code and this time autozone is suggesting a gas cap (but I just bought the new gas cap). I don’t smell any fuel while I’m driving but I’m wondering what I need to do to officially solve this problem.

FIXD Marketing

July 25, 2018

Hi Fidel,

While all of the steps that you took could have solved your problem, they are not always the issue. There may be some internal electrical issues that could be triggering this Diagnostic Trouble Code. If you end up taking your vehicle to a mechanic we would love to hear about what your issue was!

Thank you,
The FIXD Team

Concerned consumer

August 5, 2018

Check your fluid levels as well as the connections of all sensors off of the exhaust system


September 15, 2018


Didnyou ever got your car problem solved?


November 9, 2018

Is it a Chevy from 2000 to 2004?


November 22, 2018

2007 Chevy Hhr
2.2 engine


December 8, 2018

A common problem after the gas cap is the fuel filler neck got rusted and developed a crack or a hole. These holes will cause the evap leak. It usually starts as a small evap leak and progresses to a large evap leak.

Concerned consumer

August 5, 2018

Tho this app and duhicky had given me a since of security and thought that it will save me money at a mechanics shop, it is not full proof. It pays to do the up-keep on my vehicle and loom ay all of the connections as well as keeping my fluids checked and at optimum running levels. Before taking my vehicle to any mechanic I will do a once over to see what is broken, soiled, and faulty connections (loose hoses and wires). Then when I do need to go I will know if items have been replaced or not. I had this code on my vehicle for only 2 days when I found out that my oil was low by 2 quarts the engine light went out and not came back on, cost minimal. It had nothing to do with the the fuel cap or pressure system at all. I hope this comment has helped someone.


August 23, 2018


I have a code P0455 on my 2011 Chrysler 300, but no check engine light is on, I don’t smell fuel and I have one of those capless fuel filler doors. could the gas cap still be a problem? and typically how does getting this type issue fixed cost?

Jake Lawrence Allen Van Beek

September 16, 2018

I have this code and it leaks fuel while filling. How much would this cost to get fixed?

Shelly Breton

October 8, 2018

I keep getting this code with no fuel smell. The car is overheating & gives off that overheating smell. Our mechanic says they don’t know what’s wrong & a new gas cap did not fix the issue. Any other guesses as to what’s wrong or how to fix it?


October 9, 2018

Did you see if the cooling fan is disconnected. I had the same issue and found it was disconnected for some reason. If that doesn’t work, then it may need to be replaced.


November 5, 2018

Sounds like time for a new mechanic ! Did they say anything about low fluid levels or whether or not your oil pressure was low. Are you admitting white admissions out of your exhaust pipe ? How about your coolant ? Are you “steaming” it out your pipe ? is it a high mileage vehicle? So many possibilities. Joe had a good idea to see if your fan was disconnected….. if not, check all of your fuses also.

Brandon D Marshall

October 10, 2018

Where or what tubes do I perform a smoke machine test on for a chevy equinox 2005?

sc man 78

October 27, 2018

I have a check engine light on my 04 Silverado..it reads code P0455..replaced gas cap…cleared it came back on…I have just recently noticed…if the gas tank in 3/4 to all the way full the light goes off…when it drops below the 3/4 mark it says tighten fuel cap for about 3 days then the light and code come back until I fill it up again…any ideas what the issue is that’s causing this?


November 2, 2018

Hi I have a 1999 Jeep Grand Cherokee 4.0 and it makes a humming noise when idiling when the car is parked I’m not sure what it can be please let me know thanks Harrison

Roberto Sanchez

November 22, 2018

proper way to diagnose is doing a smoke test filling up the lines with smoke seeing where its leaking also making sure valves are opening and closing

Terry James

December 7, 2018

My 2011 Ford Expedition does not use a gas Capp so where would I search next.

Manthan Shah

December 7, 2018

Hi there,

I had a check engine light on twice in the last 3 months and I did reset it with an OBD II code reader.
The code was for EVAP system large leak detected.
I checked the gas cap and it was secured but the code stayed for quite a few days before I erased it.
My car economy has gone from 8L/100 kms(summer) to 11L/100 kms.(winter)
I probably use the heat most of the time.
Do you suspect a leak in the Evap system? The check engine light did not come back after I last reset it