The previous owner should have given you a card with that number. If not, look on the side of the glove box for a sticker that may have the 5 digit code. If you don't have the 5 digit code, you will need to go to an Acura dealer. They may be able to find the radio serial number, otherwise the radio will have to be removed so that you can get the serial number from the radio itself. The code cannot be gotten with the cars vin number unless that dealer has it on file.