check engine light - 2001 Accent

I have a 2001 Accent - 1.5L
My check engine light came on and I took the car to a Japanese Car repair
shop that I have been happy with.
I have had the car there about 3 times - they said the code was something
to do with fuel tank leakage of vapors. They have lowered the fuel tank
and replaced the gas cap and checked everything they could think of. Last
week they replaced some kind of a valve called a DM-TL Module (had to get
it from the dealer). 2 days later the check engine light came back on.
(the car always has been running great)
Anyone have any idea what else to look at??
Thanks for any help!!

mule

 

check your charcoal canister under the hood

 

Anything in the evap system which could leak vapors should be checked.
This includes the purge control valve, canister, vapor piping, fuel tank
and filler neck.

It may be less expensive at this point to take the car to the dealer to be
checked. The dealer has the capability with their equipment to make the
evap leakage test run and check the system. By blocking off different
areas of the system and rerunning the test, the area of leakage can be
found by process of elimination.

The shop to which you're taking your car may also have a smoke machine.
This machine fills the system with smoke and the leak is found by
searching for the area where the smoke exits. I've had great difficulty
using this method-- I can almost never see the smoke.

 

Did they check the oxygen sensor, that's what it was on mine.