Check Engine Light 99 Sonata

Hello,

I keep getting a check engine light (usually about the time when the gas
light is going to turn on) and it comes back with codes: p0442 and/or
p0455 (both for evap issues).

I spoke to someone with a 01 sonata and they had the same problem but had
it fixed under warranty and don't remember what the trouble was...

I know there are no drivabilty issues with these codes but, it is getting
annoying having to reset them all the time.

What is USUALLY the problem and where should I look... I don't want to
take it in if I don't have to because they will charge an arm and leg to
just "diagnose" the problem even after I tell them what the codes are.

Thanks for any help

 

BTW,

I did install a new gas cap that I bought from the dealer.

 

If you're getting both the P0442 and P0455, the number one problem would be
the canister close valve. But realistically, the problem could be anywhere
in the evap system. Pay for diag vs. pay for close valve that may not fix
the problem-- pay your money; take your chances.