One problem related to engine stall has been reported for the 2014 Toyota Prius. The most recently reported issues are listed below.
While driving on the freeway at highway speeds a series of yellow triangles suddenly flashed on the dashboard along with some beeps. The engine then stalled and the gas pedal no longer responded to any inputs. Due to a combination of sheer luck and driver presence of mind the car was steered to the shoulder of the highway where it came to a halt. The experience of trying to control a car with a stalled engine and safely steer it to the shoulder in heavy traffic was terrifying to say the least. The car was taken straight to the dealer where it was left for service. After diagnosis a couple of days later the dealer called back and said that the engine control module had failed which is why the engine had stalled. The car is still with the dealer since the part is not available and needs to be shipped from Toyota. The dealer claimed that this was such a rare occurrence that they did not have the parts available. They also claimed that they did not know anyone else for whom this had happened. Maybe so but this was an incident that could have been fatal. The fact that nobody got killed is just plain luck.