I don't know if it's the same procedure as I haven't had to put a code into a Honda radio, but, on the old Ford radios they had a 4 digit code with random figures 1-9 but only 1-6 preset buttons to input it with, you inputted the code by pressing the preset buttons the corresponding number of times to input that particular digit, e.g. if the first number was 8, press preset button 1 eight times for the number 8, repeating this for each digit in the code with the corresponding preset button.