First time in 10 years and 120,000 miles my check engine light has came on in my 2003 Chevrolet Tahoe with the 5.3 v8.The Tahoe is still running perfectly normal.I had the codes pulled up at the local Oreily auto parts and they came up with code #p0446 two times.Code definition states: Evaporation emission (EVAP) Vent System Performance. ...I tried replacing the gas cap with a new one, and the light didn't go off. Also, put new plugs and wires on at 74,000 miles, and a new PCV Valve at 100,000 miles. I put a new air filter in a few months ago. Anyone with a Chevrolet of GMC have experience with this code and know where I should start? I am half tempted to ignore it and its still running perfect.Thanks!!

Did you have the code cleared? I found someone that had to change the EVAP cannister vent solenoid valve to fix

Maybe disconnecting the battery for a few minutes might clear the confuser.

Get the codes cleared. With all the ethanol in the gas here in Florida, my Chevy sends false codes about every 3-4 months, especially when run hard then sitting on a cold night. I have found (and my mechanic agrees) that if you clear the codes and they come back immediately (or very soon) then YES you have a problem. With all the sensors and computer controls on today's engines and the addition of ethanol to our gasoline it's a wonder my check engine light isn't on more.

Check the vacumn hoses around the evap canister. You could have a split in one of the hoses that connects to the gas tank. After 10 years rubber tends to dry out.

If you don't clear it, it will only clear after certain amount of ignition cycles and no issue found.

check engine light came on-2003 ChevroletTahoe

Sloop_Smitten
Explorer
Dec 24, 2013
If you were indeed filling up the tank into the filler neck that can lead to fuel running into the charcoal cannister and rendering it useless. You might pull the vent lines off the cannister and let it sit for a while to allow the gas to evaporate. Or remove it and blow it out with some low pressure air. When the fuel gets in the cannister it can dissolve the charcoal and sometimes render it useless or allow some of the charcoal to get sucked back into the vent valve causing it to stick open or closed. Usually when you open the hood you can smell the fuel if it has entered the cannister. If there is no fuel smell I would suspect the vent valve.
deltamaster
Explorer
Dec 24, 2013
Make sure you only get the proper gas cap for that vehicle. DO NOT use a generic gas cap.

My 97 Dakota started throwing codes after I installed a locking gas cap. Changed back to the OEM and the code went away.

Also check all the hoses for the evap system. Maybe something worked loose.

Check all your vacuum lines as well. Maybe there is a crack or a broken joint or something that is not all the way gone but enough to reduce the vacuum enough to throw a code.

Inspect everything first. Look, touch tug a little before you start replacing stuff AND check that new gas cap.
_40Fan
Explorer
Dec 24, 2013
Dusty area? There is a filter on the vent valve that is located near the back of the fuel tank that likes to get plugged. Pull, clean, reinstall.
Crazy_Ray
Explorer
Dec 24, 2013
My Honda Accord CE came on at 96,000 miles have 194,000 now it's still on. Tried everything in the book. I don't let it bother me now.
Dave_H_M
Explorer II
Dec 24, 2013
Yep clear the code and see what happens.

Or don't clear it and if the vehicle is happy it swill clear itself after so many start ups, at least a lot of them do.
LynnandCarol
Explorer
Dec 24, 2013
yes, get the code cleared. We keep getting one from the fuel pump sensor. After it is cleared it goes away. We may have propagated it by filling the tank all the way up to the neck during top off. we stopped doing that.
MARK_VANDERBENT
Explorer
Dec 24, 2013
If you don't clear it, it will only clear after certain amount of ignition cycles and no issue found.
joegray
Explorer II
Dec 24, 2013
Check the vacumn hoses around the evap canister. You could have a split in one of the hoses that connects to the gas tank. After 10 years rubber tends to dry out.
Cooksonthego
Explorer
Dec 24, 2013
Get the codes cleared. With all the ethanol in the gas here in Florida, my Chevy sends false codes about every 3-4 months, especially when run hard then sitting on a cold night. I have found (and my mechanic agrees) that if you clear the codes and they come back immediately (or very soon) then YES
you have a problem. With all the sensors and computer controls on today's engines and the addition of ethanol to our gasoline it's a wonder my check engine light isn't on more.
Cuffs054
Explorer
Dec 23, 2013
Maybe disconnecting the battery for a few minutes might clear the confuser.

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check engine light came on-2003 ChevroletTahoe

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