Quick fix for code p0446 evap emissions vent circuit low.

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

  1. Beer Belly

    Beer Belly Rockstar

    Are you sure you are chasing the correct code....in this case, P0446 ???....I was chasing the wrong code, mine was P0449, had to replace the Evap Soleniod.
  2. i am casing the P0446. any ideas?
  3. Beer Belly

    Beer Belly Rockstar

    other than what folks are saying here about blowing it out....I have no other ideas. if by chance you have to replace the Evap Solenoid as I did, definetly don't go the dealer route, they wanted to sell me an entire upgrade kit for over $150....got the exact replacement part from RockAuto for $27 shipped, three driving cycles later the Check Engine Light went out
  4. Peckens

    Peckens Member

    check your fuel cap, wiggle it, does it move at all, even just a little? if so replace it and then clear your engine codes at autozone or advance auto. i have found that worn out fuel caps is a big cause of a check engine light b/c of a evap leak
  5. tattooed4life

    tattooed4life Epic Member 5+ Years 500 Posts

    I was told it is not that the cap is loose or worn it's that the little vents are clogged in it. Mechanic also told me that a hole the size of a human hair in the evap system can cause the error code to pop up. In other words he told me good luck finding it. I love GM mechanics. lol!!
  6. what's your thoughts on the smoke test?
  7. kinglt1

    kinglt1 Member

    Guys did you read the wrote up in my first post? po446 means your vent valve is clogged, it has nothing to do with a leak or gas cap issue. If your gas cap is leaking or there is a leak in the system, a po449 will be set. Again if your vehicle is setting code po446, either try blowing out the evap vent valve or replace it with the updated part.
  8. justcuz

    justcuz Rockstar

    If your gas cap wiggles your gasket is bad and it will allow leakage of air into the system. I replace the old gasket with an "O" ring from a hardware store. The O ring is non-collapsible and lasts a lot longer than the stock gasket.

    Code reset is easy, just disconnect negative wire from battery for a minute, then bolt it back up.
    You have to reset all your presets (radio, seat memory etc.) but it is easy. Also codes should clear themselves after a prescribed number of engine restarts, but I forget how many it is.

    The vent system cleanout is a good post, I would not however spray any WD-40 on a filter element that is supposed to be dry.
  9. kinglt1

    kinglt1 Member

    Correct use compressed air only, no wd-40 lol...
  10. tnsherrie

    tnsherrie New Member

    SES light came on and Autozone said it was throwing a code P0446. Anyone happen to know where this part would be located on a 1999 Yukon Denali 4X4? Looked up under the by the gas tank but couldnt seem to find anything that looked like a canister shown in forum pics. Any help on finding where this would be located would be greatly appreciated. Thanks

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