The GPS Week Rollover (WNRO) is a result of how the Global Positioning System was set up, and occurs once every 19.7 years. The GPS provides accurate timing information by counting the number of seconds into a week, and the week number is stored as a ten-bit binary number.
This means the range of weeks is limited to 1024 weeks in total, i.e. 19.7 years, before it rolls over to 0 again.
The most recent rollover took place on the 6th of April, 2019.
The GPS receiver chips in some devices might not be prepared for this change, and won’t be able to show the current time or your ETA.
The timing of the signals is what determines the distance from the satellites and the position of your device, so some affected devices might also not be able to get a GPS fix or navigate at all after the rollover.
TomTom has already released software updates for most affected devices that prevents any issues from the WNRO, so if you regularly update your device then there’s a good chance that it already has a fix installed.
If you want to check if your device is affected by the WNRO, go to https://www.tomtom.com/updates/ .
This page will also give you information on how to update your specific device if need be.
If you regularly update your device but want to know which software version includes the fix, click this link to see the release notes for all navigation devices.
For instructions on how to find out which version you currently have installed on your device, click this link