How to Determine Your Garmin Nuvi's Model Number
If you wish to update your Garmin Nuvi GPS unit with current maps or want to check to see if your system qualifies for a recall, you will need to know the model number of your device. Nuvi is a line of in-car global positioning systems by Garmin. If you can't remember the model number or are unsure, you can find it printed clearly on the device for quick and easy reference.
Remove your Nuvi from the window mounted cradle in your vehicle by pulling the top of the Nuvi towards you, and then lifting it off the tab on the bottom of the cradle.
Disconnect the car charger from the back of your Garmin Nuvi by pulling the plug directly away from the unit.
Turn the unit around and locate the adhesive label on the back or bottom of the device. The adhesive label includes the Garmin Nuvi serial number and model number printed on it. The model number will look like "Nuvi 255W." "255W" here represents the model number for your specific unit. Note that the model number may consist of numbers and letters, depending on your specific model.