At least 400,000 of the four million replacement inflators for defective Takata air bags will need to be replaced again in U.S. vehicles, sources at the Japanese safety equipment maker and the U.S. safety watchdog told Reuters. Another 500,000 of those parts appear to be safe, according to U.S. safety regulators, leaving the safety of more than three million replacement parts in question.
An official at the National Highway Traffic Safety Administration (NHTSA) told Reuters it was up to Takata Corp and the carmakers to “demonstrate to us that the remedy parts are safe for the life of the vehicle.” A priority now is to determine which of the replacement parts “are suspect and need to be replaced” again, the NHTSA official said.
An estimated 400,000 of the replacement driver-side inflators use a potentially defective propellant wafer that is shaped like a batwing. “Those will have to be replaced again,” the Takata source said. That estimate was confirmed by the NHTSA source.
Takata and its contract suppliers have been gradually ramping up shipments of replacement parts to manufacturers whose vehicles were equipped with nearly 34 million potentially defective Takata air bags. Those air bags have inflators that could rupture, spraying metal fragments inside cars, and have been linked to six deaths and hundreds of injuries.
A Takata executive told a House subcommittee hearing this week that the company was phasing out the batwing propellant wafers and was “rapidly” reducing production of ammonium nitrate, a volatile chemical that has been linked to inflator ruptures.
This year, about 500,000 replacement parts were made for Takata by outside suppliers, including TRW Automotive Inc and Autoliv Inc, according to the Takata source. The replacement parts from TRW and Autoliv use a different chemical from the Takata-made inflators.
“I don’t think we have any reason to suspect any problems with products from other suppliers,” the NHTSA source said.
By year end, Takata expects to provide at least one million inflators a month, of which about 700,000 will be made by TRW, Autoliv and others.
Honda Motor Co, one of Takata’s largest air bag customers, last week announced an expanded recall covering more than five million vehicles. In the official recall notice posted by the U.S. safety regulator, Honda said an unspecified number of owners who had replacement parts installed since September 12, 2014, “received an inflator of a different design, and therefore are not included in this recall."
This article originally appeared on Yahoo.