Depending on how old your TV is, there are a couple of ways to check the model code of your Vizio smart TV, as described below.
Older Vizio TVs: Press 'Menu' (using your remote), select 'Help' and then press 'OK.' Lastly, go to 'System Info' and press 'OK' again. Newer Vizio TVs: Once you press 'Menu' using your remote, navigate to System > System Information. Press 'OK' to view the information about your TV.