Toyota is voluntarily recalling 1.9 million 2009-2014 Prius hatchbacks worldwide due to a software issue.

After monitoring its own quality reporting program, Toyota said it determined a potential fault with its hybrid system boost converter. The fault is only with the Prius, not other hybrids, said Toyota.

The potential issue could happen under heavy load, during which the system can break without warning and put the Prius in a failsafe mode with reduced power, or in rare cases, it may shut down altogether at any road speed.

The repair will take 40 minutes, says the automaker, and of models affected, 713,000 are registered in the U.S., 130,000 in Europe, and 997,000 in Japan.

Owners are expected to receive mail or a phone notification of the recall.