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Evap code po440 evap system malfunction

2001 chev s-10 4.3 auto ls 2 wheel dr 116,000 miles runs and drives nice. just got it used 3 weeks ago , got this code after a gas fill up with it running… so i cleared it and it came back. so i replaced the purge silonoid on the intake and cleared the code. it seamed good but a few days later on a cold morning at start up the code was back. so what are we looking at next…what likley or commonly causing this?

Here, It’s Illegal To Fill A Running Vehicle (Fire Danger).
Have You Cleaned The Top Of The Filler Neck And Cleaned Or Replaced The Gas Cap ?


Just curious…why did you ignore every sign on every gas pump in America requiring you to shut down your engine while fueling? Again, I’m just curious. Sorry this isn’t a more helpful response, but this code is typically from some break in that system. I’m assuming you’ve tried the obvious removal/reinstall the gas cap step.

clean gas cap??? ive made sur the cap is tight…

"clean gas cap??? "

Yes, clean the gas cap, the sealing portion that seals against the filler neck and clean the neck, too. Some fillers corrode and can cause some corrosion to transfer to the cap. If both sealing surfaces aren’t smooth, an evap system leak can result.

I have had an evap leak and Check Engine light that was remedied by nothing more than cleaning the pipe and the cap and by an application of WD-40.


Are you one of those people that keeps squeezing the handle on the nozzle after it clicks off until you get every last possible drop of gas in the tank? This is the usual cause of of getting this code.

Good news, a little late for you is that if you stop this practice and stop filling at the first click of the nozzle, the problem will clear itself up in a couple of weeks, but as long as you keep overfilling, you will keep getting this code when you fill up.

BTW, it wasn’t the purge valve, it was a saturated charcoal canister that caused the CEL to come on.

The truth is that none of us can possibly have any idea what might be causing the CEL until you get the codes read and post them. The first was probably filling the tank with the engine running; do that and a CEL is guaranteed. The current code, well, you just got this vehicle three weeks ago and don;t know its history. Neither do we. The code might be entirely unrelated.

Have the codes read and post them here.

Let me reiterate it in case you didn’t get it the first time. Shut off engine while filling, no smoking, no cell phone use. Very dangerous to ignore these rules. Also as someone else said, when it clicks off the first time stop. otherwise you’re filling the charcoal canister with gas.