Auxiliary Emissions ControlOBD2 Codes

P0449 – Meaning, Causes, Symptoms, & Fixes

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Code P0449 Definition

Evaporative System (EVAP) Vent Control Circuit Malfunction

Code P0449 Meaning

The Evaporative Emission Control (EVAP) System seals the fuel system of the vehicle in order to prevent fuel vapors from the fuel tank and fuel system from escaping into the atmosphere. This is important because fuel vapors contain a variety of hydrocarbons. Hydrocarbons form smog when they react with air and sunlight. Gasoline evaporates very quickly, so if the fuel system is open to the atmosphere, a vehicle can pollute 24 hours per day without even being turned on.When the trouble code P0449 is set, this is an indication of the EVAP system vent valve solenoid malfunctioning which results in more hydrocarbons being expelled into the atmosphere.

Symptoms of Code P0449

  • Check Engine Light
  • No noticeable drivability issues
  • Fuel vapor odor

Causes of Code P0449

  • Missing gas cap
  • Damaged/Defective gas cap
  • Torn/Damaged EVAP system hoses
  • Faulty electrical connection
  • Damaged carbon canister
  • Damaged/Defective fuel tank
  • Defective evaporative vent valve

Code P0449 Severity – Low


Code P0449 does not pose any serious danger to the driver or the vehicle and there are no drivability issues that may occur. However as the case with all Check Engine Light codes, it should be fixed as soon as possible to prevent any further damage to your vehicle.

Code P0449 Common Diagnosis Mistakes

Replacing the gas cap without checking the EVAP vent valve solenoid.

Code P0449 Diagnosis Steps

Tools Needed to Diagnose:

How To Diagnose P0449

  1. Inspect your gas cap to see 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 often the fix for code P0449.
  2. Check for cracked or disconnected EVAP hoses near or connected to engine air box
    1. Replace cracked/disconnected hoses
    2. Clear code
  3. Inspect the fuel tank and charcoal canister for damage and leaks. Replace if necessary.
  4. Check your canister vent valve to test for power in the canister vent solenoid.
    1. Check out this video for a visual reference.
    2. There is a two-wire connector that represents positive and negative charges. Use your multimeter to test that there is power going through each of the probed wires (2).
    3. If there is power going to one and not the other then you have found the issue. You will need to replace the vent valve solenoid. NOTE: When you buy your vent valve solenoid remember to buy a wire harness converter (not included) that will connect with your car.
  5. If these steps do not clear your Check Engine Light, you may need to visit a mechanic because there may be internal electrical issues.


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  1. Po 449 is in reference to the electrictal part of the evap system ohm out the vent valve and u will likely find the problem

    1. How much does this cost 2 fix

      1. I just replaced mine on my 03 Silverado 5.3 it cost $34.00

        1. What exactly did you pay $34 to replace?

    2. I first replaced the solenoid located at the fuel tank
      The problem then became errant instead of constant
      I chased wires to bulkhead connection below the driver-side and found this connection severely corroded
      Had to removed rivets and replace both side of all 3 plugs.
      Fault corrected.

  2. I replaced mine. 500 Miles later the engine light came back on and the same code. GM says that the location between the gas tank and the spare tire is the problem. They say the canister gets dirty too easy. Their solution is to relocate the canister between the cab and the bed. They want almost $500 to do this

  3. I cannot get this fixd to work on my 07 gmc denaili

  4. Would the evap system cause the truck while driving down the road act like its misfiring and wanting to stall.

    1. Not the fuel cap, but he selenoid can, also check the fuel presure sensor on the top of the fuel pump

  5. Will this code p0449 cause no start?

  6. I did exactly as in the video and it worked perfectly!!! Thanks a lot!!!

  7. Nice lil site here…Love it!

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