Hey guys Auto zone ran the code for my daughter but couldnt tell her what it meant any ideas ??


Trouble code PO440
the pcm has determined that a malfuntion exists in the evaporative emission control system

I dont have a clue what its refering to.any help is appreciated

Check to make sure the gas cap is tight,if you fill the truck up and the cap is loose the first time the evap test runs it will fail and the second time it runs and fails due to the vacuum leak it will set the code.so the first thing i would do is see if the gas cap seal looks good and try that,if it sets the code again i would have it checked by a mechanic,it could have a bad vent valve are a bad purge solenoid are if the fuel pump has been recently replaced it could have a damaged seal at the fuel pump.good luck

Thanks so much for you help Stan.We will give that a try!

Hey Rad, Let us know the out-come.

Might want to check the Test Port connector, they tend to get loose at times. (It's a green colored cap)

Stan is the man !!!!! They reset the code yesterday,My daughter checked the gas cap and it was not tightened.so far so good the check engine light hasnt come back yet... thanks again

Radtexan
just remind her to make sure she tightens the fuel cap from now before she starts the truck and she will probably be alright,it is a common problem nowadays with all vehicles,people have been used to pulling up and filling up with there engines running all these years with no problems and then the EPA steps in and says we want to test the fuel vapor recovery on all vehicles,so it is a little getting used to for alot of folks.Guy's the newer vehicles test this system when the truck are car is shut down after driving to see if it see's a certain amount of vacuum decay in a certain time frame if see's more vacuum leaking off than normal it sets the check engine lite and will not shutoff for 50 ignition cycles,are it passes the test four times in a row.good luck .