I have a 2001 Elantra GLS with 132,000 miles on it and my check engine light came on and AutoZone said the error code is P0440 for the evaporative system. I got a new gas cap (they recommended this) and that made it go out for about 50 miles and then it came back on. I took the car back to AutoZone and had it checked again and as I expected it had the same code. They let me clear it so that I could find out if it would come on again and the next day it did at almost the same place it did the previous time. I can drive from home to the college and then almost all the way back home and then it comes on at about 50 miles almost exactly.

I was wondering if anyone could give me some advice on what I could do to correct this problem, I have to renew my registration but I got lucky and this time don't have to get the emissions check since I did it last year and it is good for two years only then I had to get a new flex pipe installed to pass it. However I will not know if any other problems occur because the CEL will already be on for this problem so I want to get it fixed plus it will probably be better for the car also.

I have recently on my own replaced the spark plugs & wires and the input speed sensor for the transmission both of which made the check engine light come on. I read how to replace the speed sensor here when I did that.

If I can find out exactly what needs replaced, where it is, and how to do it then I could probably do it myself unless it requires special training and equipment.

Thanks for your time.

P0440 means EVAP System No Flow During Purge Possible Causes Setting Conditions

* Charcoal canister is loaded with fuel or moisture
* Fuel filler cap is loose, cross-threaded, damaged or wrong part
* Fuel tank, fuel filler neck or fuel sending unit 'O' ring is leaking
* Fuel tank pressure sensor is damaged, disconnected or it failed
* Fuel tank vapor line(s) is clogged, damaged or disconnected
* Purge valve vapor line is clogged, damaged, or disconnected
* Purge or vent solenoid power circuit is open (check the fuse)
* PCM has failed

It sounds like maybe a bad purge valve? Maybe get on HMAService.com and see if it tells how to diagnose it. It's Hyundai's official service manual site, and you can register and use it for free. (If you don't get a password right away, go back in and do the Forgot Password thing; it seems registration only sends a password about half the time.)

had the same problem 2 times in the last couple of years both times it was the Purge conrol solenoid valve. easy to change . the part is around 40.00

Thanks, are there any directions on how to do that online or should I just take it into the shop to have it done?

Hi. On my 97 Elantra got P0442. From reading other posts it looks similar to P0440. I already changed purge valve. As error didn`t go I let dealer check it. They found by putting smoke into gas tank out that one of the hoses attached to tank is leaking. They told me I need to change those hoses but that I can do it myself. So I changed all the hoses as was told, erased code, but later after maybe 60 miles the check engine light comes out again with same code. So now I don`t know what to do. Any ideas?

My 97 has a P0451 and has a rotted line under the driver seat. Look at the three that go under the driver seat.

Good luck and keep us posted.