The transport ministry will create a database on cars that are fitted with defective Takata Corp. air bags but whose users' whereabouts are unknown, according to ministry sources.
District transport bureaus will be able to use the database to notify the users when they take their cars in for legally required "shaken" automobile inspections that they need to have the air bags repaired.
The Land, Infrastructure, Transport and Tourism Ministry is acting in response to the large number of cases in which automakers have been unable to contact cars' users to inform them of the need to recall the flawed air bags. About 9.76 million cars in Japan need repairs under the recall, but less than half have been fixed.
The ministry will have automakers submit lists of cars subject to the recall and start operating the database this summer at the earliest.
Automakers' dealers have sent direct mails and made phone calls to encourage users to get the bags replaced, but they have been unable to contact many people, mainly because they changed addresses or sold their cars.
A driver suffered burns in an accident in June, as the air bag in the front passenger's seat inflated abnormally.
The Road Transport Vehicle Law stipulates that if users change their address or ownership is transferred to someone else, they must revise their automobile registration within 15 days.
Violators can face fines of up to ¥500,000 (S$5,516), but registrations are often left unchanged.
About 7.34 million cars were reported as being subject to the recall by the end of May.
As of the end of June, however, only 46 per cent of them had been repaired.
Calculations have not yet been made regarding the about 2.42 million cars that were reported from June as being subject to the recall.
It is not known how many users' whereabouts are unknown, but the ministry believes the number is quite large.
Earlier this month, the ministry instructed automakers to compile lists of cars subject to the recall.
The ministry will cross-check this data with vehicle identification numbers in the database when the cars receive shaken inspections.
If the cars' air bags are found not to have been repaired, the branch offices will notify the users and issue cautionary notices urging them to update their registered addresses and other data.