Quick fix for code p0446 evap emissions vent circuit low.

Discussion in 'How-to Guides' started by kinglt1, Feb 17, 2009.

  1. kinglt1

    kinglt1 New Member

    As the title says: some might have an ses p0446, evap emissions vent circuit low. If you take it to the dealer they want 300-400.00 to fix the problem. GM has a service bulletin on this condition and have the updated part for 180.00, thats suppose to eliminate this issue.
    Basically the problem is, the evap purge vent valve gets clogged with dirt, especially if the truck is used in dirty conditions. Well I figured there had to be a cheaper way to cure this problem.
    Here it is:
    1) find the location of the vent valve; its under the truck, locate the charcoal canister on the front of the gas tank and trace the vent line to the vent valve.
    2) Take the bracket loose with a 5/8 wrench.
    3) Spin the valve around so the side with the hole is facing you.
    4) Take an air compressor and blow the vent valve out.
    5) reinstall and clear the code and it's fixed.

    Now I know the updated part from gm is supposed to keep the valve from clogging ever again, but why spend the money when all you have to do is blow out the vent valve every 50k-100kmi and save your $$$!

    Subject: DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Service Engine Soon (SES) Lamp Illuminated (Replace Hose/Evaporative Emission (EVAP) Canister Vent Asm) #02-06-04-037A - (02/02/2005)
    Models: 1999-2003 Chevrolet Silverado Models
    1999-2003 GMC Sierra Models
    This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 02-06-04-037 (Section 06 -- Engine/Propulsion System).
    Some customers whose vehicles are operated in dusty type environments, such as farming or mining off-road type applications, may comment about the illumination of the instrument panel SES light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set.

    Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.

    Part Number 15086429 Hose Asm-Evap Emis Cnstr Vent
    Last edited by a moderator: Jun 20, 2013
  2. MrShorty

    MrShorty Moderator

    nice write-up. Thanks for the information.

    In a lot of ways, I like your attitude. Is routine maintenance (especially something as simple as this) so painful that we have to pay through the nose to avoid it?
  3. kinglt1

    kinglt1 New Member

    Back to the top!
  4. Marty04Sierra

    Marty04Sierra New Member

    Damn, I should have found this last month. My local dealer sold me a new valve and canister for around $600
  5. zubbiez

    zubbiez New Member

    did this on my truck

    I had the same code pop up the other week and and did the same thing I just removed the purge valve blew it out with the compressor reinstalled cleared the code and tada all better.
  6. Boxman7481

    Boxman7481 New Member

    P0446 3.5L '06 Chevy Colorado

    Where is the vent valve located on a 3.5L '06 Chevy Colorado??

  7. jccams

    jccams New Member

    Tried it didn't work

    I removed the vent valve on my 2000 Silverado located between the cab and box, blew it out and had quite a bit of dust come out. I then gave it a shot of WD-40. Put it back together and reset the ck engine light. Lasted about a day before it popped again, same code 0440 and 0449. Can this valve be taken apart to more throughly clean, It looks like it would come apart?

  8. wrightj

    wrightj New Member

    i think you should be able to but i would google it? dont wanna mess it up anymore that it is
  9. kinglt1

    kinglt1 New Member

    This fix is for code p0446, not p0440 or p0449! You have a different problem!
  10. jccams

    jccams New Member

    My Chevy dealer supposidly hooked up the smoke machine and told me the problem was the vent valve.

  11. Beer Belly

    Beer Belly New Member

    I called my dealer because my check engine light came on, they want $100 just to pull the code:gasp:....I went to Auto Zone, they pulled the code for free. I was told in was the EVAP Solenoid.....more of an expense than I can afford. Will this proceedure help my situation ???...from what I was told on another website, it is caused by dirt.
  12. mrjcrod

    mrjcrod New Member

    p0440 should be an evap leak where as a p0446 is a restriction... if they did a smoke test and told you your vent valve was leaking then cleaning it will not fix it... you would most likely have to replace it...
  13. kinglt1

    kinglt1 New Member

    X2 Agreed!
  14. Peckens

    Peckens New Member

    can someone take a picture of this valve considering the picture posted tells me nothing and i can not find this damn thing
  15. ippielb

    ippielb New Member

    Look in between the cab and your box, it's on top of your gas tank, in between the cab and box, you can get down under your truck and look up, it's black and can fit in the palm of your hand.
  16. Peckens

    Peckens New Member

    so i finally had a chance to get down under the truck and take a look, after looking i found nothing on the front of the tank but i did find this on the back (rear) i took a picture now what in this pic am i cleaning?


    is this it, i found it on the pass side in the middle of the tank
    Last edited: Dec 27, 2009
  17. Beer Belly

    Beer Belly New Member

    I believe it is the first picture.....at least that is what I went after today on mine (2006 E/C).....from looking at your picture...to the left, around the other side of the canister, there is a tab that you press down on and slide the canister to your left to get it off the bracket.....with the entire thing in your hand, disconnect the wiring from the valve and twist the valve clockwise to remove it from the canister....it is slotted where it slides into the canister, so you'll need to reverse this (counter clockwise) to reinstall it back on the canister.....on the other side of this line is another area you need to seperate....it has a small clip as part of the connection that you pop off to remove it....once it is disconnected from both ends, blow it out with a compressor....reconnect. I did mine earlier, still have the light on, but I only drove it a few miles today, maybe soon it will go into a test mode and see that it's fixed (I hope), otherwise, I have no idea how to clear the code.
  18. Peckens

    Peckens New Member

    thx, was able to get under today and went exactly the way u said. i pulled thee whole thing apart and it was mighty dirty but definatly not clogged but lets hope it solves the problem
  19. i've been having the same issues and have found this posting very helpful. i have located the canister but am having trouble getting the tab pressed down. help please!!!
  20. got it off and cleaned out. the check engine light is still on. does anyone know if you have to get it reset??

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