same thing on my truck. I squirted some wd40 in the hole for the spring on the gas cap and used a nail to push the vent plunger in and out it was jamed up and now its free and no more code. I have been told it can take up to 7 days for the codes to be cleared without pulling the batery cable. Also I have made it a habbit to spin the gas cap three to four exta turns when putting gas in. Als i was tyold to never leave the truck runnig while filling the tank that give the computer a big vacume leak and make the light go on as well.