GM said in a statement to Automotive News that it is aware of two injuries related to the issue, both from carbon monoxide exposure. The problem can occur if a driver inadvertently leaves the plug-in hybrid running while it's in electric mode, which eventually will drain the battery and cause the gasoline engine to turn on.
"If the gas engine runs for a long period of time within an enclosed space, such as a garage, carbon monoxide could build up," GM said.
The Volt emits a warning chime to alert a driver who has exited the car that the vehicle hasn't been turned off. The software fix will limit the time that an idle Volt can be left in the "on" position.