Check Engine Light and P0446 Code

[2009_Suburban]

The check engine light is on, and I got the code read from Autozone, and it is P0446 which is "Evaporative Emission System Vent Control Circuit." The recommended fix is to "Replace Evaporative Emissions (EVAP) Canister Vent Solenoid" But in the description, it refers to the broken part as a "Failed Purge Valve"

 

Rockauto Lists

Vapor Canister Purge Valve / Solenoid  and  Vapor Canister Vent Valve / Solenoid Which one should I get?   Also, how certain is it that this part failed? Is there something else that is wrong that could have created the code?

[richard wysong]

the best way to figure it out is to get the diagnostic tree from the service manual or Alldata and follow it. Codes DO NOT mean replace the parts

[2009_Suburban]

My Haynes manual doesn't have it, and the Alldata and service manuals I could find are expensive, and only last a short time. Are there any other options?

Edited April 17, 2022 by 2009_Suburban

[richard wysong]

You could try a library or if you know any one at a local garage they may print it out for you. maybe someone here can help with a download. I go see a friend at a local garage and use their Alldata when I have to research a problem. some NAPA stores have Alldata and will print it out for you. did you ask at AZ? j

[richard wysong]

this would be a good thing for Rock Auto to offer their customers, it would probably  cut down the number of returns but may also  cut into sales to people who just fire the parts cannon

[Brenden Burnham]

If you know someone with a code reader that can look at live data you should test in real time fuel tank pressure sensor, and EVAP Solenoid.  Best way is to look at Live Data.  Your fuel tank pressure sensor should be at 1.5v atmospheric pressure.  If it is not close to that then that is the issue.  Check video for what I am talking about.  It most definitely could be the Purge Valve but instead of firing off the parts cannon if possible check to see if it is getting correct volts.  

 

 

Edited April 17, 2022 by Brenden Burnham

[Brenden Burnham]

Usually if it is the Evap canister typically it will have a loose or cracked hose or the box itself is done.  They tend to get moisture in them and during winter they freeze thus causing possible cracks.  Simple enough to check under car and examine the evap box/hose.  

 

Also could be something as simple as your gas cap. Check and ensure it is not cracked or could possible be leaking.  I one time forgot to put back on my gas cap after starting up the truck and it threw a P0446 code.  It cleared after just 10 miles of putting back on the cap and starting correctly.  

 

And lastly if you are still getting the code it is best to take it in and do a smoke leak test.  This will tell EXACTLY where it is leaking. 

Edited April 17, 2022 by Brenden Burnham

[2009_Suburban]

I think I fixed it with the help of this video:

I found the vent tube filter not attached up closer to the filler tube, and it was dangling, but not that low. It and the filters inside were caked with dirt. I took the filter meshes out, banged them against a rock a bunch of times to get all the dirt out, put them back in, and zip tied the hose up where it was supposed to be. After disconnecting the battery, and driving for 20 minutes, the code is not back.

 

Are there any other vent filters similar to this that could also have the same problem and require cleaning?