The other day while installing my tanabe exhaust i unplugged my battery (reasons unknown) and when i reconnected it i found out my radio needed a code to work again. I lost the paper that had the code so i went to the dealer. In order to get the code one must have the radio serial number which can be seen by.....
1) have key in and turned to second click (just have the radio on i guess)
2)make sure the radio is off
3)hold down the #1, #6, and then hit the Power button (volume knob) and a number should appear on the screen.
That would your radio's serial number and using that the people at the Honda dealer can use it to find what your code is to make the radio work properly again. Not sure if this is covered in the manual but i found it interesting and wanted to share it with you guys