Auxiliary Emissions ControlOBD2 Codes

P0455 – Meaning, Causes, Symptoms, & Fixes

P0455 system gross leak evaporative system malfunction

What Does Code P0455 Mean?

  • P0455 definition: System Gross Leak Evaporative System Malfunction
  • Issue Severity: LOW– Continued driving for a short period of time is okay.
  • Repair Urgency: Get this code fixed withing the next month to prevent issues related to the emissions system including failed inspections.
  • Diagnosis: It is important to complete the entire diagnostic process when diagnosing the P0455 code. This DTC can be triggered by just about anything in your vehicle’s EVAP system from a loose gas cap to a defective part.

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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. The vent control valve is normally opened when the engine is on, and the purge volume control valve is normally closed and is controlled by the ECM to open when it is ready to purge the stored fuel vapors from the charcoal canister.

However, the ECM occasionally performs leak tests to ensure the evaporative emission control system is working properly when the vehicle is turned off. During the leak test, the ECM closes the vent control valve to create a sealed EVAP system. 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.

P0455 Causes

  • Missing, defective, damaged, or loose gas cap (*most Common)
  • Faulty or stuck EVAP vent control valve
  • Faulty or stuck EVAP purge volume control valve
  • Cracked or disconnected EVAP hose
  • Cracked or damaged charcoal canister

P0455 Symptoms

  • Check Engine Light is on
  • A slight decrease in fuel economy
  • Gasoline smell
  • Commonly associated with error codes: P0440, P0441, P0456, or any other EVAP-related codes

How Do I Fix Code P0455?

With a P0455 code, the first step is to get it properly diagnosed to figure out what is causing the malfunction in the EVAP system. Using the live data function of the FIXD sensor and app allows you to read and analyze fuel trims to properly diagnose a P0455 code.

If you have checked your gas cap and other common issues associated with this trouble code and haven’t been able to diagnose this issue at home, we recommend finding a RepairPal-certified shop to pinpoint the problem and give an accurate estimate for repairs. 

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

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How Much Does It Cost to Fix Code P0455?

If you take your car to a shop for diagnosis, most shops will start with an hour of “diag time” (the time spent in labor diagnosing your specific issue). Depending on the shop’s labor rate, this typically costs somewhere between $75-$150. Many, if not most, shops will apply this diagnosis fee to any required repairs if you have them perform the repairs for you. From there, a shop will be able to give you an accurate estimate for repairs to fix your P0455 code.

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Possible Repair Costs for P0455

When it comes to making repairs associated with the P0455 code, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair. 

  • Gas Cap $20-$60
  • EVAP Line $20-$100
  • EVAP Vent Control Valve $150-$200
  • Purge Volume Control Valve $150-$200

DIY Steps to Diagnose Code P0455

If you’d like to try to fix code P0455 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Diagnosis can require some specialized equipment beyond what the FIXD Sensor can provide, but this is usually still a beginner-level diagnosis. 

DIY difficulty level: Easy

This repair is easy enough for beginner-level DIYers to attempt.

Tools/parts needed (our top picks from Amazon):

  • FIXD
  • Pliers or screwdriver to secure a loose hose(s)
  • EVAP smoke machine leak checker
  • Vehicle specific service manual

Use FIXD to scan your vehicle to verify P0455 is the only code present. If other codes are present, they must be addressed first. If it is paired with P0441, P0440 and/or P0456, there is most likely a solenoid failure or a more complex EVAP leak.


Inspect your gas cap to see if it is loose or damaged. If your gas cap is loose, tighten it and clear the code. 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 is not always noticeable. If your gas cap was not loose and you do not see any indications of failure, try replacing the gas cap anyway and clearing the codes. Gas caps are relatively inexpensive and are often the fix for code P0455.


If the fuel cap didn’t fix it, perform an EVAP system leak check. To do this, pinch off the vent tube to the EVAP Vent Control Valve. Pressurize the EVAP system with an EVAP smoke machine leak checker. Check to see if you see any smoke leaking out from any hoses or seals. If there are any leaks, repair leaks and check to see if the concern is resolved.


If at this point the vehicle is still setting the same code, you may have an electrical problem and will need to bring it to a shop to have further diagnostic work performed.  

Common P0455 diagnosis mistakes

It is important to complete the entire diagnostic process when diagnosing P0455. Don’t overlook a loose or faulty gas cap as this is the most common culprit that cause the check engine light to come on for this code.

Still Need Help Fixing Code P0455?

If you’ve followed the steps above and are still experiencing a lean engine condition and code P0455, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.


Lifelong automotive enthusiast with a soft spot for offroading. Wrencher turned writer, but I still love to tinker on just about anything with an engine. Dream car: tie between a ‘71 Hemi ‘Cuda and a ’91 GMC Syclone. #GirlDad #SaveTheManuals

Jeffrey N. Ross
Lifelong automotive enthusiast with a soft spot for offroading. Wrencher turned writer, but I still love to tinker on just about anything with an engine. Dream car: tie between a ‘71 Hemi ‘Cuda and a '91 GMC Syclone. #GirlDad #SaveTheManuals

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

    1. 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.

    2. Check your fluid levels

      1. 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.

    3. It’s not going to be y your engine I most cases it’s going to be by either your gas tank or the actual evap canister… depending on what make, year, and model your car is, that location could be anywhere, I would suggest getting a Haynes manual specific to your make and year, they will show you where it is and what you need to do

      1. This code came up and I have noticed loss in fuel economy.
        Should I still purchase new gas cap to start?

    4. I have a P0455 code on my 2002 Nissan Xterra. Im going to address this issue but I’m having trouble with my truck stalling while idling and I don’t believe something is small could be the issue. My distributor, spark plugs, radiator hose, battery, starter etc are all new. What could be the issue?

      1. Could be your mass air flow sensor sounds like you are not getting enough gas vs air

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

    1. 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

      1. I have a 2004 Cadillac Escalade im smelling gas on the outside of my truck but not on the inside could it be purge valve or canister

  3. 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.

    1. 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

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

      1. I have been having this code for a year, off and on. Changed gas cap with the push button cap that is supposed to give better deal or something. Anyway light comes back on after a couple days. Last fall put a used evap canister on and it was good for a month, then light came on.
        Interesting… If I put about half a can to a full can of Seafoam in before I fill up tank, light will go out on its own and never comes on. Unless I fill up without putting Seafoam in first. Problem is a net part is $450 at stores. So with labor it would be $500-$600. 2006 Subaru Forester.

        1. Si es la boquilla de llenado de gas yo también remplase todas las válvulas y el problema fue la boquilla de llenado o el cuello de la tapa

    3. Fidel,

      Didnyou ever got your car problem solved?

    4. Is it a Chevy from 2000 to 2004?

      1. 2007 Chevy Hhr
        2.2 engine

        1. I have a 2007 chevy and this problem is driving me insane!!! I changed the gas cap, the evap canister vent valve, the purge valve, the carbon canister, and had the hoses checked and still the same code!! Im about to switch back over to Japanese import, never had an issue with my Japanese cars

          1. I have a Japanese car and have the same issue though. Code P0455 and it’s not the gas cap but my 2011 Camaro has no issues related to this

          2. Ese código lo tiene mi carro y por donde sale el gas es por la boquilla de llenado de donde está la tapa y se puede comprar sólo la boquilla de llenado

    5. 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.

      1. I have a 2010 Chevy Tahoe that has had this problem for 5 years. I’ve paid to fix every part on the codes that I know of. The solenoid, purge canister, cap 3 times. I just paid to fix the purge canister again and another smoke test and the darn light is back on after the 100 mile mark. The only thing that I noticed from Purchasing the car is the gas pumps shut off quite a bit while I pump gas. Any ideas? I’m so tired of seeing the check Engine light on that I greatly appreciate any feedback

        1. Did you every fix this problem Alisha?

          I have the same problem. It’s been going on for two years. I’m ready to fix it for good.

          My last ‘fix’ was airplane epoxy on the rollover valve on the gas tank. That’s where the smoke was coming from. That held up for 6 months.

          I’m thinking about replacing the whole tank this time.

          1. Although this is an old thread, but maybe someone else can benefit. You may have a bad pressure sensor, try replacing it. Also if you have a bad charcoal vapor canister sometimes the charcoal pebbles from the canister rolls out into the vacuum lines and block them. Disconnect the vacuum lines from the tank and clear the lines by using compressed air

    6. My 98 F150 is throwing this code and running rough at idle. It stalled the last time I drove it but still starts, drives, and runs. I’m wondering if that rough idle is a clue to what my issue is?

  4. 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.

  5. Hello,

    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?

    1. Hello Sandra, did you ever get your issue with code PO455 resolved?? It could simply be your EVAP pressure Sensor is gone bad or the EVAP vent valve needs to be replaced. It typically cost around $300-$450 for this repair. However, I do have an alternative for you. Download the app called. “ your mechanic”. They are mobile ASE Certified mechanics (just like at a mechanic shop”. But these mechanics will come to your home or office to repair your vehicle. For a little bit less than what a mechanic shop would charge. And they also provide a warranty with their work. Hope this helps.


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

  7. 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?

    1. 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.

    2. 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.

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

    1. same vehicle i am having issues with, if you figure out what is wrong with yours let me know

  9. I have a check engine light on my 04 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?

  10. 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

  11. 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

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

  13. 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

    1. Hi folks want to fix this problem too upon a Dodge Ram – trying a process of illumination- Cap first then reset and so on.
      But one thing I cannot find on the APP – is how to clear the warning – can you help

  14. You tube. Your code and car…

  15. I don’t understand why these people always say that the gas cap is the most likely solution. In my experience it’s never the solution. I’ve dealt with this problem on two vehicles now, replaced the gas cap first in both instances of course, and surprise, surprise it didn’t fix the problem. I was lucky with my 2010 Dodge Avenger and it was just a vent canister, but with my girlfriends 2006 Chevy Malibu Maxx on the other hand, no luck and a pure nightmare. We’ve spent over $800 with mechanics who have done their so called “tests” and we still have no idea what it is. I guess we’ll just have to replace the entire emissions system just to have some other code pop up as soon as we do so. The title of this section and video should be “P0455 Code? Time To Buy A New Car” cause they clearly also don’t really know what this code means.

  16. What if you got a delete kit and delete it all of the Emissions?? You’re my car only sputters when I’m going faster than 60 I just don’t know what else to check

  17. This code came in on my 2003 Avalanche, and the problem turned out to be a bad O ring on the canister purge solenoid. I didn’t have the correct O ring, so I just put a little heavy grease on the O ring, and that cleared the problem for about 9 months. The code just came back today. Guess I will break down and buy a new solenoid this time. I hope this helps some of you Chevy guys.

  18. Black electrical tape over the check engine light works real well.

  19. I did have a bad gas cap rubber o-ring seal causing the evap leak code. Cleaned the inlet tube orifice real good and took a new o-ring seal off the gas cap that wouldn’t work I bought at advance. Noticed the OEM cap when holding in hand and twisting while holding the end that goes into the tube and it was spring loaded and would snap back. The one I purchased at Advance was not spring loaded and would not work, but the o-ring fit on my old cap and fixed it. Now check engine light came on again and read faulty downstream O2 sensor. While underneath vehicle I noticed that the hose coming from charcoal canister wasn’t connected to anything but had a pressure clamp on the end of it. Couldn’t find where it connected, but assume it goes to purge valve and that section is missing. Oh, by the way it’s a 14 Avenger. Don’t buy one…

  20. I have this code combined with P0171 and P0174. Any thoughts on where to look? All three codes always throw simultaneously.

    1. The po171 and 174 are codes that mean your engine is running rich and then lean because of the 455 code .The computer is compensating for the vacuum leak. Hope this helps.

  21. Hello all, I bought a 2020 Camaro at the end of April of this year. Within the past 2-3 months the check engine light keeps coming on. I’ve had it in the shop 4 times now, each time they replaced either a solenoid, the neck from the gas tank to the gas door, and then another sensor that I can’t remember the name of. The car does not have a gas cap. I just got the car back yesterday and it is on again today. So I’ve had the car less than 6 months and this will be the 5th time putting it in the shop. It’s still under warranty but this is getting ridiculous. I emailed GM today to see what they say, hopefully they will have a solution.

  22. Hello! Another symptom was gas not going in my car. When I tried to fill up my gas it would stop as if full after putting minimal amounts into the tank.

    1. Don’t put the nozzle all the way in

  23. 2012 Honda Fit has large evap code. Replaced gas cap, purge valve and vent valve. 2 mechanics told me they couldn’t help me. Another mechanic did smoke test in 2 places, found no leaks and suggested I take it to a dealer. Any ideas?

    1. When I had my 2012 Kia Rio diagnosed (need to pass smog) at the dealership for a P0455/P0420 code combo their report came back with the same two valves that need replacement. They also suggest my cat converter needs to be replaced.

      The catch? The cat has already been replaced in my Rio previously. I have been the only owner. Very very frustrating. I’m planning on trying to clean the O2 sensors to see if that changes anything before breaking the bank over that repair cost again.

  24. I bought this new evap canister. Bought new purge valve. Should have no issues. I do a dyno test. You Should Put The Same Car.Should Put The Same Year Car

  25. I have a code po455. I changed my gas cap, but the engine light is still on. I do smell fumes. I was also told I’m missing a filter for my vent. Would that cause a PO455 code?

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