Why does my 2002 cadillac deville check engine light pop on and off occasionally? the car drive fine but the light still pops on and off

Hello: The check engine light is telling you there is a problem. To diagnosis and repair you need to go to Auto Zone, Advance Auto or O'riely auto parts stores and have the code read. Then you will know what is causing the problem. You could also go to a GM dealer. There are about 100 things that can cause
to come on.