Had the code for awhile. Not the gas cap.No leaks that I can find. Could it be the vent valve?

Yes, evap charcoal canister solenoid in the rear of the car most likely, or the wiring harness that goes to it. My 01 LS had this happen and the wiring harness was streched and cracked. One of the wires actually separated from the harness and that's what threw the code. Many others have had the same problem with these cars.

i think my 03 had that code and it was evap, so i replaced it.


APC: Autozone Playas Club

well, it could be anything, because what the evap system monitors basically is supposed to be a completely sealed (most of the time) containment for gasoline fumes. the vent valve opens to allow vacuum from the engine to draw the fumes into the charcoal canister, where they are temporarily held. this puts the gas tank under a vacuum, which the tank pressure sensor reads how well the tank is holding the vacuum. once the engine is warmed up, it will then open the purge solenoid, drawing the fumes into the intake to be burned along with the air fuel mix. so, what you have is a system where and stuck valve (vent or purge), any cracked line for the evap system, a bad fuel fill hose, a cracked canister, a broken wire/disconnected harness, and yes, even the gas cap can cause the computer to throw a code. now i had the P0440 code with my car (96 2.2), and tried many different things. i re tightened the gas cap, code still there after clearing. i unplugged and plugged back in the tank purge harness, code remained. i checked all the lines i could find, all looked ok, but if there was a pinhole, i would have missed it under the car (canister is up front passenger side on mine). then one day i was installing my tachometer sending unit, and realized that the valve on the back of the engine was never plugged back in after my rebuild. i plugged it in, cleared the code, and bingo! no more 0440. sorry for the long post, but i figured I'd shed some experience on this issue


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a piece of black electric tape to cover the check engine light... or in my case, a picture of my girlfriend. haha. mine throws the same code, been too lazy to fix that. its been 100+ deg. w/ 50%+ humidity.. that motivates the laziness.


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I just got the same code on my 97 2.2. My dad and I were looking for broken wires everywhere and couldn't find anything. So, we cleared the code and decided to take it in to our shop where we have better tools and everything. I went to get gas because I was on E, and I noticed all my gas was on the ground instead of in the tank. WTF. There is a decent sized hole in the filler tube going from the gas cap to the tank, right where it is supported by the frame. Regardless of whether that is causing my CEL I ordered the tube from gmpartsdirect.com because it has to be fixed anyway, but I am almost positive that is what is throwing my code. It is acting like a bad gas cap because it is releasing pressure. I haven't got the part yet, so I will post if that fixes the problem or if the CEL comes back.

yeah... that'll do it...



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