Toyota has announced that it is recalling 1.9 million Prius hybrid models worldwide. However, reflecting fast changing automotive technology, this recall is not caused by a mechanical issue, but by the need to update the vehicle software.

A fault with the Prius computer operating system can cause the vehicle to slow down suddenly and the carmaker has identified more than 400 reports of the problem, but stresses that no accidents or injuries have occurred. The issue has mainly come to light in North America and Japan where the Prius has recorded record hybrid sales.

The recall is on newer generation Prius models made since March 2009. It is believed the problem causes the car to go into a failsafe mode where only a reduced amount of driving power is available. In extreme cases the car could stop altogether.