Toyota (NYSE:TM) affiliate Daihatsu rigged part of the door in side-collision safety tests carried out for some 88,000 small cars, most of which were sold under the Toyota brand, the companies said on Friday.
Daihatsu said it had discovered the rigged safety test after a whistleblower report. It said it had reported the issue to regulatory agencies and stopped shipment of affected models.
They said the door trim on the affected vehicles had been modified with a "notch" to minimize the risk in testing that the door interior could break with a sharp edge and cause injury to an occupant when the side airbag deployed in an accident.
Toyota Chairman Akio Toyoda said the companies were investigating how the side panel of Yaris and other models had been changed for safety testing and apologized for what he called an "unacceptable" violation of consumer trust.
It was not immediately clear who had rigged the doors for crash testing, how widespread the knowledge of the action had been within Daihatsu and whether senior managers had approved the step.
"We'll proceed with a detailed investigation from here on, but promise to decisively understand what happened at the site, investigate the true intentions and sincerely work to prevent a recurrence," Toyoda told reporters.
"We're going to need some time to do that," he said.
Toyota said it had not received any report of an accident or injury related to the rigged side-crash test.
The affected models include Toyota Yaris Ativ made in Thailand from last August, and Perodua Axia manufactured in Malaysia starting from February.
Daihatsu said it would run new safety tests in the presence of regulators and confirm the safety of the models before resuming shipments.
"We have to find the cause of what happened, including examining the environment in which it happened, and once we've confirmed that to take appropriate action to address the underlying cause," Toyota President Koji Sato said.
"We can't run away from this or hide," he said.
Shares of TM are down 0.57% in mid-day trading on Friday.