troubleshooting P0440
OBD2 domestic
i went to autozone to run the check but this is all the info they gave me
it also helps around here if you at least make an effort on your part to find your information. i cant even count how many times i've posted this.
i wrote: 0440 relates directly to the evaporative emissions system. the parts that it monitors include (from stern to stem): the gas cap, the gas fill neck, the gas tank, the gas tank pressure sensor, the vacuum lines running from the tank to the evap canister, the canister itself, the valve on the canister, the lines from the canister to the purge valve, the purge valve itself, and finally, the line from the purge valve to the intake manifold. 
if any one of these 16 parts is faulty, it could trigger the 0440. the most common place to begin diagnosis is with the gas cap, as if not screwed on tight enough (by yourself or the gas station attendant) -or- if the rubber on the cap has degraded enough to not make a seal, then this code could be thrown. a gas cap should not cost more than $6-$8 at your local parts tore. next, a visual inspection of the lines to see if any are cracked, broken, kinked, or otherwise pinched off/leaking. if, after these inspections have been made and determined to not be the cause of the problem, i wold recommend getting your emissions system smoke tested.the parts after these simple diagnoses can get quite expensive depending on where you get them from, and as such, you'll only want to change the part thats causing the issue.
now the diagram may say up to 00 models, but the 01+ models still have the same parts, just in different locations.
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I had the same thing. Start with the gas cap, make sure it's on nice and tight. A couple of restarts should reset the light if it's that. If it doesn't go off after a little while, or you notice something else wrong, it's probably not your gas cap.
I'd say to get Autozone to clear the code for you, like I did with mine, but so far as I know that's illegal now.
If you can manage to get them to clear the code for you, I'd try that and see if it comes back, if it doesn't then it was the gas cap (like mine), and if it does, start going down the checklist.
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