If you disconnect the battery to reset the ecu, it will lock the radio and require an unlock code in order for the owner to use their radio.

The unlock code is usually with the vehicle paperwork when purchased from the dealer.

alternatively, if you're ever in a bind, this website from Honda will use the magic of the internet to retrieve your radio code:

radio-navicode.honda.com/

All you need to do is provide the VIN, Name and Address and Phone Number that you supplied when you bought the car, and the radio's serial number (which can be found with a couple pushes of the radio buttons).

Who knew?

Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma