Final answer:
A diagnostic scan tool is required to view immobilizer codes, which are part of a vehicle's anti-theft system that prevents the engine from starting without the correct key.
Step-by-step explanation:
To view immobilizer codes, a diagnostic scan tool must be used. Immobilizer systems are designed to prevent a vehicle from being started without the correct key or fob. This anti-theft feature uses a code that matches the key to the vehicle. When troubleshooting immobilizer issues or performing key programming, mechanics or technicians use a diagnostic scan tool to read these special codes, communicate with the vehicle's onboard computer, and potentially diagnose any problems with the system.