dont even worry about it the 1693 code is a code to tell you there is a code, i get this code all the time i never had any problems because of it, most often the 1693 code is stored and stays there it does sometimes go away so i say drive it till it acts up

You can have what is called pending codes that will not set a light on the dash ,but will store the code to see if it will come back in the furture.

that might be it?