Just had this email from TomTom: it may require YOUR attention! Your satnav has always been there to guide you, now it needs your help. On 6 April 2019, the GPS Week Number Rollover may impact your satnav. We are here to help you check and guide you through next steps. Get started below. Mine was OK - Gordon The GPS Week Number Rollover (WNRO) occurs every 19 years, with the next roll over taking place on 6 April 2019. Similar to odometers in older cars rolling over from 99,999 km to 0, the GPS WNRO is the resetting of the GPS calendar back to 0. When the calendar resets, it can cause a miscommunication between GPS satellites and GPS receiver chips. As a result, some chips in satnavs will lose the ability to process certain functions.