What does Flashing check engine light mean on a 2014
Hyundai Sonata Gls

 

Technically, it means the engine in your vehicle is polluting one and one half times more than the legal limit.
Now what does that mean to you,,,,,,,,,,,,,, you will either attempt to see what codes are in the vehicle's computer or have your vehicle checked for any codes.
Are you noticing any roughness in the operation of the engine, called misfires.?

If you don't have any means to get the codes, places like Autozone will do that for you at no charge.
I suspect you will get something like a P0300 and others possibly directing a mechanic/technician to a specific cylinder. There may also be other codes and the best thing is to wait and see what they are. Something very important,,,,,,,,, if the vehicle is driven like that for any length of time it can affect the exhaust converter and they are expensive to replace.