so for a while i thought i had the p0466 or whatever which was small evap leak
some odb 2 codes can read them wrong and one guy even suggested my truck had the codes backwards according to a repair manual
so i told the guy at the parts counter at gm dealership
bought a gas cap cleared code
a day later cel comes back on
tell parts the light came back on he suggests buying the vent valve so i do
he also talks about how i should notice that the tank isn't being fully pressurized and so when filling the truck up the nozzle will click every few seconds (which it has never done)
replaced the vent valve (didn't do the relocation thing as it was a different part or part of a kit or something)
2 weeks later and the light came on last night :ouch:
next up is the solenoid i guess?
i also took the truck in to look for a 03-05 cts and they only offered 4k for my truck so
looks like ill be keeping it a little longer or look for something cheaper! :shocked:
(as gas prices are really hurting right now)
Don't know what year you have but my 03 kicked that code so since I don't have the proper tools to diagnose evap problems (knew it wasn't gas cap). I took it to the dealer to get smoke tested. They called bck and said that the vent valve was stuck open. So I had them replace it all in all I believe it cost a little over $300. To me it was worth it due to me just replacing parts and crossing my fingers.So far thats the only thing they have done for me.
Now my buddy has a 99 his kicked the code out so he took it to a private shop they said they smoked it and his vent valve was stuck open as well. Well they replaced it and the next day his light was back on. So we took a look under the truck and I noticed the fuel filler neck had some small rust pin holes in it. So he ordered a new one we put it on and he has been good to go for over a year now. So after his experience with that shop make sure you find a reputable shop. Hope this helps.