On certain vehicles, a problem with the power steering system could cause it to turn off while driving. The power steering assist may return when the vehicle is restarted.
Safety Risk
A loss of power steering assist would result in a sudden increase in steering effort, especially at low vehicle speeds. This could increase the risk of a crash.
Corrective Actions
General Motors will notify owners by mail and advise you to take your vehicle to a dealership to replace the power steering gear assembly.