The check engine light will flash if you have a misfire bad enough to do catalytic converter damage. If your check engine light is just on solid, then it is o.k. to drive your car as long as it is driving o.k.
Now why does a misfire burn up a cat? I will tell you about it now: The catalyst is engineered to burn the excess fuel Not burned in the normal combustion process. When the spark does not light the air and fuel mixture in the cylinder, the unburned fuel and air go into the catalytic converter where they are burned up, remember the catalyst is nor designed for this, so the cat simply overheats and melts. The cost for catalytic converter can cost between $300 and $2,000!
I hope this information has been useful to you!