Auxiliary Emissions ControlOBD2 Codes

P0449 – Meaning, Causes, Symptoms, & Fixes

What Does Code P0449 Mean?

  • P0449 definition: Evaporative System (EVAP) Vent Circuit Control 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 P0449 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 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.

P0449 Causes

  • Missing, defective, damaged, or loose gas cap (most common)
  • Defective EVAP Canister Vent Control Valve
  • Distorted, damaged or cracked Fuel Tank Filler Neck
  • Torn or punctured Evaporative system hose(s)
  • Defective Fuel Tank Sending Unit gasket or seal
  • Split or damaged Carbon Canister
  • Defective or damaged fuel tank
  • Open or shorted electrical connections

P0449 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 P0449?

With a P0449 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 P0449 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 P0449?

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 P0449 code.

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Possible Repair Costs for P0449

When it comes to making repairs associated with the P0449 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 P0449

If you’d like to try to fix code P0449 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 P0449 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 P0449.


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 P0449 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 P0449?

If you’ve followed the steps above and are still experiencing a lean engine condition and code P0449, 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. 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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