RDFLYER

Hello Guys, I have a 2005 C6 which has near 70k miles on it. I don't have any significant mods on it except a Billy Boat exhaust and Snakecharmer intake which were put on in 2006. Never had a check engine light come on as long as I bought it new. I noticed the check engine light when I made a trip to Tucson and had a friend with a OBD II tester and it scaned for codes but no codes found,So for kicks we cleared it(the no code) and the light still stayed on. I de-powered the computer by dis-connecting the battery for about 15min, and then restarted the car and the light went away(no codes found again by the OBDII. However after two hrs of driving home the Check engine re appeared!!! Any Idea's or experience with this situation?? Thanks,
Al