If the light doesn't go out on it's own you should use the OBDII plug to pull the trouble code. My light came on awhile back and the code told me it was the temp probe, it had come unplugged because I didn't make the new leads long enough. Fixed the problem with longer wires and the light went out after I deleted the trouble code with the reader.
Oh yeah, I forgot to tell you that part, the trouble code readers have the ability to delete stored codes. Deleting the codes is what turns off the light. If you turned on the key while the temp probe or something else was unplugged it stored a code.