'03 Impala LS Check engine/service light

Im havin some troubles with my '03 Impala. The engine light/service light has been on for quite some time now. I took it in to a certified Chev dealer to have them hook up the code reader. The mechanic at the dealership said that there was nothing wrong with the car :banghead: . It still bugs me. Does anyone else know what it could be or how I could reset the engine light? A lot of people wont buy my ar because of it. If anyone could offer any help I would greatly appreciate it.

Thanks,

Hunnybunny

First, what engine and how many miles on the car?
I don't think it is possible to have a check engine light without a code being stored. I'd go back to the dealer and ask for them to scan it again. Write down whatever codes you find, and post them.
Some trouble codes can be erased be disconnecting the battery for about five minutes, but not all of them.
Are you having any problems besides the light? When did it come on (under what driving conditions)?