[zippy_gg]

The PO should have given you a card with the security code.
Same thing with VW and Audi and you have to get a code from the dealer where they check the VIN, etc... Of course they will charge you for this.
This is designed to reduce car radio theft by making them harder or impossible to sell by thieves since the units don't work without the code.
If your unit is a third party you may try an auto sound reseller, but chances are they'll try to sell you a new one.