OK I have a code problem and emissions coming soon. I have done tons of research. I have changed the vent solenoid mounted near the gas tank. Code came back. Now let me let all of you know what I have done since. Put Vaseline on the gas cap seal and the purge solenoid o-ring where it plugs into the manifold. Cleared the code and it came back. So today I looked at the filler neck vacuum lines to the charcoal filter box. They all have rust but don't think they are leaking. Now I do have a question. How often is the purge solenoid mounted on the manifold, on? I put a vacuum meter on the purge solenoid, on the top where the plastic line is connected. It took a little while before it opened and the vacuum was on. Meter read about 18. So I took the meter off and hooked the hose back up. Went to the Charcoal filter and pulled the hose off the filter and put the meter there. Same, 18 on the meter. Now there are 2 other hoses on the charcoal filter. Should I have vacuum on the other 2? I am thinking to change the FTP sensor on the fuel tank next. Not sure what else to check. Any help would be great. Thanks

 

I'm now having the same issue on my 05' Suburban. Any updates?

 

I changed 3 things and the fault was cleared. Cost about 60 bucks. The purge sensor mounted on the frame near the charcoal canister, the gas cap, the last was the sensor mounted on the top of the gas tank.

 

the purge solenoid is on the engine not in the frame rail, that's the vent solenoid. Something to check for if you live in a dusty area or are on dirt roads much is the vent solenoid and canister will get filled with dirt and a lot of times intermittently cause the vent solenoid not to seal. Where I live about 98% of the time theres a p0446 its because the vent solenoid and canister have ingested dust/dirt.

 

I changed the two valves already, will probably do the cap next. I hope that solves it and it's not the tank pressure sensor as suggested by someone in the thread I started.

 

Every time, and it has been more than once, it was my gas cap that was no good. Can't see anything wrong but that was the issue.