Fiat Chrysler Automobiles NV recalled about 4.8 million U.S. vehicles to fix a software glitch that could keep a driver from being able to deactivate the cruise-control system.

The Italian-American automaker advised customers driving select Ram pickups, Jeep SUVs and Chrysler and Dodge brand models to avoid using cruise control until the software in their vehicles is upgraded. The U.S. National Highway Traffic Safety Administration issued an advisory to “strongly encourage” that consumers follow the directive.

While the recall is significant because of the sheer number of vehicles -- the number of cars, SUVs and trucks involved exceed Fiat Chrysler’s total U.S. sales during the last two years -- the costs may be less severe because the repair involves a software fix. Fiat Chrysler said it’ll start alerting customers as soon as next week and that it’s unaware of any injuries or accidents related to the flaw.

The company’s U.S. shares extended their decline in early trading, falling as much as 3.9 per cent, and were down 2.5 per cent as of 9:25 a.m. in New York.

The recall affects 15 models from as early as the 2014 model year to brand new vehicles and includes top sellers like the Jeep Grand Cherokee and Wrangler SUVs, Ram’s 1500 pickup and Chrysler’s Pacifica minivan.

Fiat Chrysler said that in certain driving conditions, its cruise control systems automatically initiate acceleration to maintain speed. In an “an unlikely sequence of events,” automatic acceleration could occur simultaneously with an electrical network short-circuit and could prevent a driver from being able to cancel cruise control, according to the company.

The automaker said that the cruise control acceleration can still be overpowered by braking.

 An unspecified number of vehicles in Canada will also be recalled. 

-- With files from BNN Bloomberg