Some of the world's biggest auto manufacturers have admitted incorrectly handling safety testing on several vehicles over the past decade.
Japan's transport ministry found Toyota, Honda, Mazda and Yamaha submitted incorrect or manipulated safety test data when they applied for certification of some vehicles.
The government has forced the companies to halt shipments of some vehicles as a result.
The latest revelations came after the ministry requested automakers investigate certification applications following a safety test scandal at Toyota's Daihatsu compact car unit that emerged last year.
That scandal resulted in Daihatsu factories being closed down.
Toyota apologises
The wide-ranging faulty testing at Japan's top car-maker, Toyota, involved the use of inadequate or outdated data in collision tests and incorrect testing of airbag inflation and rear-seat damage in crashes.
Engine power tests also were found to have been falsified.
Toyota said its wrongdoing occurred during six different tests conducted in 2014, 2015, and 2020.
The vehicles were three production models — the Corolla Fielder, Corolla Axio and Yaris Cross — and discontinued versions of four popular models, including one sold under the Lexus luxury brand.
Toyota suspended production of the Corolla Fielder, Corolla Axio and Yaris Cross in Japan.
The company said the wrongdoing does not affect the safety of the vehicles already on roads, which include the Corolla subcompact and Lexus luxury vehicles.
"We sincerely apologise," Toyota Chairman Akio Toyoda said, bowing deeply at a news conference in Tokyo.
Toyota said it is still investigating issues related to vehicle fuel efficiency and emissions, and aimed to complete that inquiry by the end of June.
It added there were no performance issues that violated regulations and customers did not need to stop using their cars.
A Japanese government investigation into Toyota began in January, with the problems not extending to the company's overseas production.
Shareholder pressure likely
Monday's developments are also likely to heighten focus on Toyota's annual general meeting later this month.
Influential proxy advisory firms Institutional Shareholder Services and Glass Lewis have recommended shareholders vote against re-electing Akio Toyoda as chairman at the meeting.
In a report to shareholders, ISS singled out the "spate of certification irregularities" at the Toyota Group.
The scandals at the manufacturers are proving to be a sore point for the government, which has otherwise earned praise from investors and executives for its corporate reforms.
Yoshimasa Hayashi, Japan's top government spokesperson, called the misconduct "regrettable".
Toyota shares closed down 1.8 per cent.
Mazda suspended shipments of its Roadster RF sports car and the Mazda2 hatchback from Thursday last week after finding workers had modified engine control software test results, it said in a statement.
It also found crash tests on two other models, which are no longer in production, had been tampered with by using a timer to set off airbags during some frontal collision tests, instead of relying on an on-board sensor to detect a hit.
Mazda shares fell 3.3 per cent.
Yamaha said it had halted shipments of a sports motorcycle.
Honda said it had found wrongdoing in noise and output tests over a period of more than eight years to October 2017 on some two dozen models that are no longer being produced.
AP/Reuters/ABC
