2016 eco with 9800 mIles and I get a check engine light out of no where. I did put premium fuel in but had gone through almost 1/2 a tank before the light came on. Could it be the higher octane fuel? Can higher octane hurt the engine?

 

No. Higher octane is not to blame. It can't hurt the engine. Opposite is true. If you have a 91 octane tune, but run 87 you can get premature ignition, or knock. But not the other way around.

Unless the fuel was somehow contaminated, it has nothing to do with your engine light. Have the dealer check out the DTCs stored in the engine ECU.

 

Gas door not sealing causing evap leak code?

 

Already double checked the gas cap/door

 

it could by any of the O2 sensors, crank potion sensor, fuel pressure sensor and so on. Your dealer or even autozone can read the codes and tell you.