Quick fix for code p0446 evap emissions vent circuit low.

**kinglt1** · 02-18-2009, 12:09 AM

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

**MrShorty** · 02-18-2009, 12:28 PM

nice write-up. Thanks for the information.

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 $$$!

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?

**kinglt1** · 07-13-2009, 11:18 AM

Back to the top!

**Marty04Sierra** · 07-13-2009, 11:37 AM

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

**zubbiez** · 07-13-2009, 11:59 AM

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.

**jccams** · 09-22-2009, 10:45 AM

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

**wrightj** · 09-22-2009, 12:42 PM

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

**kinglt1** · 09-28-2009, 01:44 PM

Originally Posted by jccams

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

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

**jccams** · 10-05-2009, 07:34 AM

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

Jeff

**Beer Belly** · 10-05-2009, 09:29 AM

I called my dealer because my check engine light came on, they want $100 just to pull the code

....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.