US regulators say there could be more recalls of airbags made by the Japanese firm Takata.
They are said to have contacted seven carmakers seeking information.
So far driver and passenger airbag inflaters have been recalled on nearly 20 million American vehicles sold by 11 companies including Honda and Fiat Chrysler.
It was found that the airbags can inflate with excessive force, spraying metal shrapnel. They have been linked to eight deaths and over 100 injuries worldwide.
In June the chief executive of Takata apologised for the defects.
The seven carmakers contacted by the US National Highway Traffic Safety Administration (NHTSA) are reportedly Mercedes-Benz, Jaguar-Land Rover, Suzuki Motor Corp., Tesla, Volvo Trucks, Volkswagen AG and Spartan Motors Inc. Shares in the affected carmakers fell upon news of the potential recall expansion.
The NHTSA estimates that the number of defective inflaters installed in US vehicles is 23.4 million, lower than previous estimates of more than 30 million.