Quick fix for code p0446 evap emissions vent circuit low.

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

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  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).
    --------------------------------------------------------------------------------
    Condition
    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.

    Cause
    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 1000 Posts 100 Posts

    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 100 Posts

    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 100 Posts

    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??

    Thanks!!
  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?

    Jeff
  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.

    Jeff

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