What are and what to do about these codes

[ranger690]

I pulled codes this morning because the cel keeps comeing on and off everyday and this is what I got 117 and a 617 I think I have gotten the 117 before but never the 617

I mainly want to know what would fix these codes

Thanks,
Kyle

 

[jmpSHO]

117 is a bad ECT sensor. Not too sure about the 617 though.