Toyota Motor Corp. and Nissan Motor Co. issued recalls Wednesday for 6.56 million vehicles world-wide over problems with Takata Corp. air bags, citing new findings about the risk of moisture seeping inside the devices.
The recalls come in addition to roughly 25 million vehicles already recalled by more than 10 auto makers since 2008 over Takata air bags. At least six deaths have been linked to air-bag explosions.
“Among the parts collected from the Japanese market, certain types of air-bag inflaters were found to have a potential for moisture intrusion over time,” Toyota said in announcing the recall of five million vehicles. “As a result, they could be susceptible to abnormal deployment in a crash.”
The reference to moisture intrusion, which Toyota said it hadn’t mentioned previously, could be another clue to the still-unidentified cause of the air bag explosions. Nissan said it found a similar defect on a passenger-side air bag.
Air bag inflaters contain propellants, which are explosives that emit gas and fill up the air bag. If moisture seeps inside air bag inflaters, it could damage the propellants. That in turn could cause the gas to get emitted too quickly, leading the metal casing of the inflater to explode.
Takata uses ammonium-nitrate based propellants, which experts say tend to be sensitive to absorbing moisture. Rivals including Daicel Corp. do not use ammonium nitrate in their propellant chemical mix, industry insiders say.
Toyota cautioned that the relationship of moisture intrusion to inflater ruptures, if any, remains uncertain.
Toyota plans to replace driver-side air bag inflaters with ones made by Daicel, while replacing passenger-seat air bag inflaters with newly manufactured Takata ones.
The Toyota recall affects 35 models produced between March 2003 and November 2007, including 1.36 million units in Japan and 637,000 in the U.S.
Nissan separately announced a recall of 1.56 million vehicles with model years between 2004 and 2007, affecting 288,000 cars in Japan, 326,000 in North America and 563,000 in Europe. Honda Motor Co. said it was considering additional recalls.
“Takata will give full cooperation to the auto makers,” a Takata spokeswoman said, declining to comment further.
An official at Japan’s transport ministry said the recalls by Toyota and Nissan were made pre-emptively. He said the ministry hasn’t received new reports of accidents related to Takata air bags.
In March, Takata’s chief executive, Shigehisa Takada, said an investigation being conducted by Germany’s Fraunhofer Institute on behalf of Takata was in line with the company’s initial analysis that age and long-term exposure over many years to persistent heat and humidity were significant factors in the air-bag inflater malfunctions.
A group of auto makers that have recalled vehicles over the faulty air bags are jointly conducting a probe, while Honda Motor Co., Takata’s biggest customer, is doing its own examination. U.S. and Japanese regulators are also investigating.
Takata said earlier this month that it hopes to return to a profit in the business year ending March 2016, after recording a ¥29.6 billion ($247 million) net loss in the 12 months to March 31 tied to recall-related costs.