I just started occasionally getting this code on my 2002 Z71 Magnacharged Avalanche. It currently has 88k miles on it. The code is for Evap vent control circuit so I assume the valve is not closing properly to allow the Evap system test to pass.

Is there any reason I shouldn't just set the code to "don't report" and uncheck the SES-enable box with HPTuners? I can't think of any good reason as I don't believe there will be any negative effects.

 

76 views and nobody has experienced advice or knowledge? I was hoping someone would chime in with confirmation that there will be no performance, drivability, or safety related issues.

I have currently set it to give the SES light on the second failure. The Avalanche is not my daily driver so it may take a while to see if that worked. If not, I guess I will just have to uncheck SES-enable, set to don't report, and monitor what happens.

 

I shut mine off years ago - no problems yet- (02 z71 also)

I think you can take and blow compressed air In there to clean it up. Might want to flip it upside down while doing it. Google it -it's common issue in dusty conditions

I have also a p0449 code which I think that part is like 20 bucks these days. i never got around to fixing mine

 

I just bought the part for like 25 bucks at napa and tossed it in my truck, fixed my issue.

 

So a thought just occurred to me that the P0446 code may be part of an issue I noticed with the truck the past 6 months or so - a hard start condition when the truck is fully warmed up. The starter cranks longer than the "normal" for the past 13 years. I'm going to replace the fuel filter first.

I hate to start throwing parts at the issue without diagnosing, but I'm sure I can buy the purge valve, the evap vent valve, and the charcoal canister for less than a shop would charge for a diagnosis. If the fuel filter doesn't take care of it, and I doubt it will, I plan to start with the evap vent valve as the most likely issue, then do the purge valve, followed by the charcoal canister.

What's everyone's thoughts about this plan?

 

Check your fuel pressure regulator- take vent hose off and see if it's wet- if wet it's bad

 

I decided to pull the canister vent solenoid off the truck tonight and take a look at it since this seems to be the most common failure mode due to dust accumulation if you drive on gravel roads, which I do on a somewhat regular basis. It was pretty full of dust so I checked on a price; it was $30.99 at O'Reilly so I bought one and installed it. I'll be a happy camper if this was the issue and this one lasts another 13+ years like the original. If this doesn't correct the hard start when hot issue I'll probably do the purge valve and call it a day if that doesn't work.

 

I thought I would update this thread in case someone does a search in the future. I've not had a re-occurrence of the code since replacing the vent solenoid.