The only CLARION code available for free (using a serial number ) from anywhere on the Internet is if your radio also has a BARCODE SERIAL NUMBER beginning with C 7000000 + + + + on a label somewhere on the metal casing.
If not then it will only be available from your Main Dealer or a Decoding Service or your local Car Radio / Audio Store who will connect a laptop to read/recode the memory chip (EEPROM)