The recall mainly affects certain Prius variants produced between October 2008 and November 2014, the auto maker said Friday. See the chart below.
While these cars were created to enter this mode in response to certain hybrid system faults, this may not operate as intended.
Another 830,000 are reportedly in North America, 290,000 in Europe, 3,000 in China, and the rest in other parts of the world.
It is the second recall for the Prius in the space of a month, with the previous one involving more than 1 million hybrid cars due to the risk of fire.
Power steering and braking would still work, but a stall at a fast speed could increase the risk of a crash. Toyota did not say how many customers reported stalling incidents, whether there were accidents, or when customers could bring in their cars for fix.
Toyota said it was not aware of any actual accidents caused by the fault.
"Toyota has found that in rare situations, the vehicle may not enter a failsafe driving mode as intended".
Toyota says it will use a software update to fix an issue with some Prius models, saying certain conditions could result in them unexpectedly stalling. "All auto owners are encouraged to routinely check their vehicle identification number (VIN) for any open recall on Nhtsa.gov/recalls".
"If this occurs, the vehicle could lose power and stall".
The auto maker said that it was not aware of any crashes due to the issue in Japan.
In 2015, it had to recall 6.5 million vehicles globally over a faulty window switch that was liable to short-circuit.