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The thread you want to read is "quick fix" for p0446. There are several causes for the 445 and 446 codes but I think this one covers about everything.

https://www.gmtruckclub.com/forum/threads/quick-fix-for-code-p0446-evap-emissions-vent-circuit-low.18964/

Ted
The thread you want to read is "quick fix" for p0446. There are several causes for the 445 and 446 codes but I think this one covers about everything.

https://www.gmtruckclub.com/forum/threads/quick-fix-for-code-p0446-evap-emissions-vent-circuit-low.18964/

Ted
Pulled the canister and it is full of loose pellets, so it needs replacing. The small line that has the blue retaining clip is stopped up with pellets. Do I blow into the canister end or the other end, and is the other end the on the purge solenoid on the engine?
 

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Topping off the tank is verboten. Gas in an underground tank is way colder than ambient. After you top it off it will expand and travel through the evap system. You'll see the result when you open the canister and hoses there. You can possibly clear them by opening BOTH ENDS and using shop air. Sometimes they need replacing. Don't blow charcoal into your fuel tank.

Edit: You keep saying no codes. Didn't this start with a stored P0445?

Ted
The only code I initially had was P0455 and I with Tighten the gas Cap. I cleared it after tightening the cap and have not had any codes since. Took the canister off and it is shot, carbon is pouring out of the large pipe. The small hose with the blue lock is plugged with pellets. It must be the vacuum line from the Purge solenoid on the engine. Is it safe to to disconnect the line from the Purge solenoid and blow it toward the disconnected end that was attached to the cannister?
 

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You don't want to blow charcoal pellets where they don't belong. Make sure each hose is disconnected at both ends before you blow it out. I've never had to do this. If it's not to much trouble then remove each hose completely one at a time and reattach so you don't mix them up. A new canister is filled with charcoal pellets but they aren't soaked with fuel.

Ted
 

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Every once in a while I choose to read a post, such as this one, that has been resurrected. As I start to read, I get excited because @Motor City Rick is back, then I see the dates and am disappointed all over again!
 

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For a while we had a user, screen name of Motor City Rick, he has some posts on the first page of this thread. The guy was amazing at knowing what the fix was. Especially if it involved wiring and needing wiring diagrams. He must have had every shop manual from the beginning of GM until now available! He just disappeared. We all miss his wisdom and guidance! He probably got tired of all of us " idiots asking childish questions" that @mommatried84 couldn't handle either!
 

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I think he wore his two fingers out. :cool:

Ted
 

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Topping off the tank is verboten. Gas in an underground tank is way colder than ambient. After you top it off it will expand and travel through the evap system. You'll see the result when you open the canister and hoses there. You can possibly clear them by opening BOTH ENDS and using shop air. Sometimes they need replacing. Don't blow charcoal into your fuel tank.

Edit: You keep saying no codes. Didn't this start with a stored P0445?

Ted
Disconnected vacuum line at Purge Solenoid and it and line full of carbon beads. After multiple shop air blow outs all beads cleaned from line. Cleaned solenoid and as soon as tank comes I can put it all back together. Thanks for your help!
 

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Got a code in Sept. the Vap Solenoid failed. Replaced the one under the vehicle near the gas tank. Two months later I am getting tighten gas cap notice on dash. Cap was tight and good but bought a new one since it was the original one from when I bought it in 05. Still getting notice on dash. Have not checked for codes yet. Will do it tonight when I get home. The other day I forgot the gas cap off after filling up the tank, would that cause me to be getting this notice on my display?
 
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