If you are chugging down a freeway or looking for an address this weekend and your Satnav goes haywire you could have a problem.
Satnavs and other devices relying on GPS technology may have to be replaced with a new model scientists have warned with the witching hour set to be 12pm on Saturday.
Retailers have not said whether they are carrying extra models of Satnav should consumers have a problem.
Some analysts claim users will simply resort to Google maps.
Motorists, sailors and pilots using GPS technology could all be affected especially if you own an older model satnav system. The most affected are set to be Tom Tom Navman and and GTarman devices.
Other more worrying areas where a GPS chip is used is the electricity grid, which could also be hit, experts warned.
The warning has been issued by the National Physical Laboratory in the UK as well as several satnav makers who expect the timing system on many older models due to reset – or ‘rollover’. The problem is similar to Y2K that affected Australian computer systems in 2000.
The NPL said the effects of the ‘GPS rollover’ were ‘truly unpredictable’.
But it could mean the time and date – as well as the estimated time of arrival at destination – going wrong in your car’s satnav, with a software update needed to fix it.
Other impacts could be on financial traders who use GPS to record trades, and ports which use GPS information for the loading of ships.
The problem arises because when GPS was invented in 1980, the date and time was represented by a counter that could only count forward a maximum of 1024 weeks, or about 19.7 years.
TomTom has advised customers to ensure their satnav is updated, or to upgrade it to a more modern device.
‘When GPS was first created, the processing power of computers was not what it is today, and limiting the week number to just 10 bits helped to keep down the amount of data that had to be transmitted. ‘
TomTom on its website said: ‘Similar to odometers in older cars rolling over from 99,999 miles to 0 miles, the GPS WNRO [week number rollover] 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 navigation devices will lose the ability to process certain functions.’