"Due to a communication error within the electric-drive system, the electric powertrain unit may shut down, temporarily immobilizing the vehicle and resulting in a loss of propulsion power," said NHTSA in its recall summary. "A vehicle stall increases the risk of a crash."
A stop-sale order has been issued to Mercedes-Benz dealers until the cars are fixed.
The affected B-Class cars were built from November 21, 2013 to May 26, 2015.
A Mercedes-Benz spokeswoman did not respond immediately to a query from Edmunds asking if there are any injuries, crashes or fatalities linked to the recall.
Mercedes-Benz dealers will update the electric-drive system software. The recall is expected to begin in December. Owners can contact Mercedes-Benz customer service at 1-800-367-6372.
Edmunds says: Owners of these cars should wait for their official recall notice and then set up a service appointment with their dealer. But if you have an immediate concern, it's a good idea to contact your dealer now.