Sorry newbie here and posted this originally as a reply. My MIL light is on.

Hi KatMcG, Is there any reason that you think the MIL is related to a loose gas cap, or were you just checking the basics? The MIL will illuminate for thousands of different reasons...the only way to really know why it is on is to use a diagnostic computer to check the code(s) and then perform the diagnostic test(s) required for the code(s) that are turning the MIL on. If you are not a trained diagnostic technician, your best bet is to bring the car to a professional...it will obviously cost you some money, but in the long run, it will save you lots of headaches, money spent on replacing parts that may not need to be replaced, and will save you from possibly causing damage due to driving the vehicle with worn out/failed components. Jason Advanced Auto, Inc.