Hi all...

Im sure you have ALL heard of the infamous P0440 code. EVAP leak...I think it means large EVAP leak. Anyways, mine is on...umm...wont go away, I've flashed it numerous times. Changed the gas cap. Car has been in an accident in the front and back, I think that's the cultprit. It keeps coming on after about 50km. Meaning the system is filling up, and leaking as predicted. Should I change the EVAP canister solonoid? Any ideas? Ya, thanks. I hate P0440....

What engine/year?

I'd start by examining the evap lines... from the evap solenoid on your engine, back via the flexible plastic line to the firewall (assuming it's a 99+ car), then the metal line back to the charcoal canister...

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.

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im still stuck on the po0440.. replaced purge solonoid.. charcoal canister.. charcoal vent.. gas cap.. lines look fine.. i guess its time to take it in..........

"Z24 Dustbunny"

Did you clear the code?

i did, keeps on comming back every 500 miles or so...................................

"Z24 Dustbunny"

500 miles? not bad...you dont have a big leak, so be happy. Mine is every 50km (30 miles). Soo, I have a large leak. I will check the lines soon and get back to you guys. It starting happening after I powerwashed the engine (stupid). Damn Ecotec...wiring is iffy too.

i replaced my ld9 and mine came up 5k miles later... i got a locking gas cap and it happened around that.. i replaced it and it still popped up..... erg. but be sure to let me know where your leak was..

"Z24 Dustbunny"

gm has a bulletin on a faulty harness on the evap system in the rear of the vehicle

On the little black box! Yes...faulty as in? Cus I can drop it and check the connections...

FYI: It's pretty much a useless code. There is no reliability, performance, or cost issues. You may lose a TINY bit of gas vapours, but thats it as far as I know. I just might give up, not really important is it.

Minor Power & fuel economy loss
and im sick of that cel bein on all the freggin time.. everyone gives me crap about it haha

"Z24 Dustbunny"

can pass inspection with an 0440. fan comes on, saps horsepower and fuel economy. the cel is on so its annoying, you wont know if something else goes wrong.



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if you have a small leak it doesn't affect anything really, fuel economy or power. with a large leak it's possible. remember that if you get a code for the small evap leak, the leak can be as small as the diameter of a human hair to throw off a CEL. thank you obd-II! anyway, in this case you're better getting a smoke test done and see where the leak is instead of just replacing parts left and right. and one more thing: i heard it's better not to re-set the CEL after you find the leak and fix what causes it. leave it on. if you really fixed the problem it will go off by itself provided that your car doesn't throw a totally different and unrelated code.