If the light is just on, then safe to drive. If blinking, then stop and see what it is. Mine has blinked one time, it was misfires because I had overfilled the oil and it overwhelmed the AOS and sent some oil back through the intake. Once I let some oil out it was all fine.
I remember my first CEL, I had the car only a week or so, and I had just filled up with gas at Costco. On the way home, idling at a light, it came out. My heart sank. I felt sure that the car was about to implode. I got the code read and it was O2 value something or other. I immediately planned to replace all 4 sensors... $$$. Luckily I came to my senses, as it is rarely the sensors themselves; they are just what indicate the fault condition.
Later on it turns out that my passenger side O2 sensor was bad, and replacing it solved one of the issues that was causing the CEL (the heating was bad on that sensor)
Here's a good article on sensors, with part numbers (I got mine from amazon) but keep in mind it usually is not the sensors.
https://sites.google.com/site/mikefocke2/oxygensensors
Here's a good article on CEL:
https://sites.google.com/site/mikefocke2/acheckenginelight%28cel%29
Good luck. Once you get the code read, come back to the forum and search on it, and you will most likely find tons of info.
Steve