The National Highway Traffic Safety Administration is warning drivers about “cheap, substandard replacement air bag inflators” in used cars that can fail to prevent serious injuries or death in a vehicle wreck.

The agency said Wednesday that three people have been killed and two suffered severe injuries in the past nine months due to substandard, aftermarket air bag inflators.

“If consumers own or are considering the purchase of a used vehicle, NHTSA urges them to learn their vehicle’s history and ensure their vehicle has genuine air bag inflators,” the agency said.

In each of the five cases in which someone was killed or injured, the vehicle had previously been involved in a crash and the original airbags were replaced. Malfunctioning airbag inflators sent “large metal fragments into drivers’ chests, necks, eyes and faces, killing or severely injuring drivers in otherwise survivable crashes,” according to NHTSA.

Other cheap inflators may deploy too slowly, or partially, meaning occupants of a vehicle may strike the dashboard or steering wheel in a collision.

Anyone in the hunt for a used vehicle should secure a vehicle history report, or do so now if they did not before buying a vehicle, the NHTSA said Wednesday.

If it is determined by a car dealership or a qualified mechanic that a vehicle has a faulty air bag inflator, the NHTSA advises replacing them and notifying a local Homeland Security Investigations office, or FBI field office.