I have an Ultragauge - when the CEL comes on, it is telling you that a code has been set. So read the code!
Guessing at what your code is would be a waste of our time and yours - who the hell knows what it is!

And............
By knowing what codes are being generated, you keep ahead of trouble. As the car ages, you WILL see that light more and more. Mine kept coming on, caused by misfire codes and O2 sensor codes - I had all the plugs and plug wires changed, no trouble since then. Had I taken it to a dealer, they would have put O2 sensors in it as well, but I knew that misfires can cause O2 codes so I didn't have them replaced right away. Glad I didn't.

I really think that it is about DAMN TIME they displayed codes in the odometer window, but that's just me. Until they stop treating customers like fools, (mostly to get you to go to the dealer and pay for something you can do yourself) you need an easy to use device to read codes yourself. Give us the code, and you will find that the fix is usually straightforward and not all that expensive. Unless you go to the dealer. Do not take one of these cars to a dealer.