Niall Posts: 11,114
edited December 2021 in Navigation Devices
Make sure your device has the latest application software version.
For a full list of compatible memory card for UK devices see this FAQ; for USA devices see this FAQ; for Australian devices see this FAQ

The ideal card is a Sandisk 16Gb class 10 (max 32Gb)
  1. Insert card and perform a soft reset by holding the on/off button firmly in until a drum-roll is heard and then releasing it.
  2. When the device restarts, that is when it will recognise the card and ask if it can format it, to which you answer yes.
  3. If it fails to format the first time, introduce the card to your computer and perform a full FAT32 format on it and restart from 1.

After the card has been formatted by your device it will not be readable in your computer, as Tomtom use their own proprietary file format.