Service Engine Soon Light

My service engine light soon just came on. My car has about 57,000 miles on it.... anyone have any suggestions as to what it could be?

[jabartram]

Without a scanner there is no telling? How is it running?

[FormulaNERD]

has it went off yet? most likely running rich, may be O2 sensor or something, autozone will check it for free....

meh, i left the battery disconnected for like 20 min and the then tried it and the light went off. Is there a preset time when the light is supposed to go on.... o btw it was 58000 not 57000 miles...