Auto supplier Takata has told US lawmakers that it is yet to identify the cause behind the explosion of its air bags, but refused to extend the recalls to all the 50 states of the US.
The Japanese company suspects high humidity to be the cause for the air bags to explode spilling metal shards into the cars.
Reuters quoted Takata safety executive Hiroshi Shimizu as telling the Congressman: "We don't identify the root cause yet."
"But we are of the strong opinion that (there) is a factor contributing to this defect: which is high humidity, temperature and the life of the product."
The defect has been linked to five deaths, and over 16 million cars have been recalled worldwide so far. In the US, recalls were imposed in Florida, Puerto Rico, Hawaii and other humid regions.
Expansion of the recall to the remaining US states would affect eight million more cars. However, refusal to recall may prompt the US National Highway Traffic Safety Administration to fine the autoparts maker up to $7,000 a day for each unrecalled car on the road, reported the BBC.
Meanwhile, Honda and Ford have decided to expand their recalls in the US Honda has agreed to recall its cars using Takata air bags from all the US states.
Ford will pullback around 38,500 vehicles more, increasing the total recalled cars to 98,000. However, it will restrict its recalls to humid regions.
Toyota Motor said that it will recall around 190,000 cars - 185,000 in Japan and 5,000 in China.
