My check engine light is constantly on....a guy at the kia place told me that it was because I prob didn't tighten my gas cap enough. He stated that if I took it to a kia place they could turn it off but I don't live anywhere close to one. Can I fix this myself??

yes
ignoring lights leads to complacency and a large repair account that could have been avoided if attention was paid in the first place
exhaust light codes are in the p1400 list and refer to the EGR valve system ( exhaust gas recirculation)
I would find an accredited service center that has experience on your make of car and have the fault codes read and the problem properly diagnosed
what you dealer stated about the gas cap is an EVAP issue and if he didn't read the codes first , he has done you a disservice and not attended to your concerns properly

Can't dismiss or second guess what you were told

Auto Parts Store counter people are not mechanics
or techs

Check for codes,then diagnose

Test,test,don't ask questions

Hello, have you tried to unhook the negative side of the battery for about 10 minutes and then go from there . It should reset the computer completely .

The gas fillup should be clue, either the gas cap was not tightened enough or it is defective.

Check the gasket on the gas cap if it's in good shape try tightening the cap firmly.

P0442 EVAP Leak Monitor .040 Leak Detected (Medium Leak)

P0456 EVAP Leak Monitor .020 Leak Detected

replace your gas cap and clear codes, then wait and see if light comes back on, if it does you have a more serious problem like a fuel tank leak or a defective fuel tank pressure sensor.

Just replace the air flow meter.That sounds like your problem.

Check the metal tabs on the gas cap they should be aligned with the little groves if there not the cap won't go on correctly or close all the way and you will get the engine light coming on. Happen to me and I used a pair of needle nose pliers to move the tabs back into place (wasnt easy) and then it worked fine...Hope this helps you.
Kelii
P.S my cap got like that after I fueled the car and was in a hurry now I make sure everything lines up before I tighten it.

Are you tightening your gas cap enough after you fillup?

I had a problem also w/ the ck engine light and was told to click the gas cap when putting it back on after a fillup.

Problem never returned.

I had the same problem. I went to the kia dealer and they checked the code that caused the light to be on and found I had a leak in the gas cap. They replaced the gas cap and the problem went away. You night need to find out what made the check engine light go on in the first place.