Help! Help! Help!

Posting this again here in the galant section, I have this post in tech forum also, sorry to be repetitive.
I just purchased a used 00 galant ES, sold as is therefore no warranty and new to this brand. I've always and still own a toyota so I need some info on any little quirks on this cars maintenance as well. Back to the problem, this car has 96,809 miles on it and being used I don't know how it's been treated other than it is completely mint almost inside and out, the owner obviously adored it. My service engine light is now glowing after my 1st two trips for errands tonite. I don't have a manual either so therefore I don't know if this means a serious technical issue is happening or possibly a service change reminder of some kind, I'm cluleless as there are no signs of any engine problems such as noises, odors, or smoke. My tech savy step-father even did a thorough inspection before purchase. With the year model and mileage is there any known particular up front issue I should address first? Should I continue to drive to find problem or stay parked and seek dealer help?

Clueless and fearful
Amanda

 

have the dealer perform engine diagnostic.