P0446 code on low mileage 2018 Tahoe

[auto_cran]

New to the forum - first post.

My wife drives a 2018 Tahoe RST (5.3) that we bought new. It has just under 8,000 miles (COVID, WFH, company car drastically changed our driving habits).

She loves it, but for the past few months we have been getting the dreaded P0446 code (Evaporative Emission Control System EVAP vent control circuit malfunction). I have been clearing the code with my scan tool, but after a hundred or so miles, the code returns.

Online research typically points to a clogged filter at the rear of the vehicle, but those seem to occur on vehicles with high miles and/or when driven in dusty/dirty conditions - neither of which applies to our Tahoe.

Any suggestions/ideas on what I should look for or do? I can do some minor wrench turning, but all I've had to do with this Tahoe so far is change out the battery. Oil changes done by dealer. Vehicle is bone stock.

Thanks in advance.

 

[Doubeleive]

New to the forum - first post.

My wife drives a 2018 Tahoe RST (5.3) that we bought new. It has just under 8,000 miles (COVID, WFH, company car drastically changed our driving habits).

She loves it, but for the past few months we have been getting the dreaded P0446 code (Evaporative Emission Control System EVAP vent control circuit malfunction). I have been clearing the code with my scan tool, but after a hundred or so miles, the code returns.

Online research typically points to a clogged filter at the rear of the vehicle, but those seem to occur on vehicles with high miles and/or when driven in dusty/dirty conditions - neither of which applies to our Tahoe.

Any suggestions/ideas on what I should look for or do? I can do some minor wrench turning, but all I've had to do with this Tahoe so far is change out the battery. Oil changes done by dealer. Vehicle is bone stock.

Thanks in advance.

here are some basic things to look at/for, 8k is very early to have this issue.
often it is just a small leak, so check those lines over real good.
I woudln't be so concerned with a tank pressure sensor as mentioned at the end of the video, if it is not a leak then it is either the canister or one of the solenoids.
if you decide to replace any parts I highly recomend using oem for this issue, aftermarket parts tend to not work as well and often fail quickly, causing the issue to return.
one thing to note as well is this issue can be tricky to troubleshoot because it takes 3 drive cycles (vehicle completely cooled down_to operating temp and back again) for it to self check and pass, this is why it comes back after 100 miles as noted.

 

[B-train]

I would contact your local chevy dealer. With that low of miles I would assume its under warranty, or good will. I thought most emissions components carried an 8yr/80k warranty.

 

[Doubeleive]

I would contact your local chevy dealer. With that low of miles I would assume its under warranty, or good will. I thought most emissions components carried an 8yr/80k warranty.

the factory cat's might be but that's about it once you are past the bumper to bumper time/mileage whichever comes first.
but probably worth a try anyway. the dealer will either say yes or $120 kind of a roll of the dice.

 

[Rygrego]

The standard Federal emissions warranty is 8 years or 80,000 miles and California emission standards are longer. This would be covered under emissions warranty.

 

[auto_cran]

Thanks for all the responses!

That video is very helpful - I was ignoring the gas cap/filler neck since there is no gas cap - but that video shows I should at least look at it and confirm it's sealing OK.

If the issues still exists - I'll swing by the dealer and find out if its covered under warranty. Then go from there.

I'll report back any findings.

One nice benefit - I discovered this forum and am having a great time reading the posts and learning new things about this cool vehicle.

Thanks again!

 

[Doubeleive]

The standard Federal emissions warranty is 8 years or 80,000 miles and California emission standards are longer. This would be covered under emissions warranty.

not much is covered beyond manufacture warranty (ca. get's a few more mileage allowance) basically it's cat's and a select few things, evap is not covered in this persons case under federal or ca. unless he is in ca and it turned out to be a vapor valve and not a evap valve

 

[Doubeleive]

the sucky part is if you take it to the dealer they "might" say it's a $180 diagnostic, then once they determine the part needed you may or may not get credited towards that part on the diagnostic+ labor. (ask them questions to clarify)
for $180 you could shotgun it and most likely fix the issue yourself. or gamble and buy just the suspect part and potentially save more.
there is only 3 parts that commonly go bad: canister, vapor vent solenoid, evap solenoid. unless you get unlucky and have a cracked line or something.
the canister is $115 on amazon
the evap solenoid is like $30 almost anywhere
the vapor vent solenoid didn't see a price for oem on a quick search but the total is going to be close to the diagnostic fee the dealer charges alone
it's a roll of the dice lol, you could maybe fix it or the dealer could maybe stick it to ya diagnostic+parts+labor
using aftermarket parts for this stuff is not advisable, they tend to fail much faster than oem, goes along with fuel pumps and a few other things.