These are almost always fraudulent. Users who try them report either wasted time, stolen personal information, or a bricked navigation system that no longer shows even the compass screen.
For certain models (especially those with Uconnect 4C NAV or later), you can buy an activation directly online: free uconnect navigation activation code
Avoid any website or service that:
: The code is permanently linked to the vehicle's VIN and cannot be moved to another car or refunded once used. These are almost always fraudulent