Shares in Mitsubishi Motors have fallen more than 15% after the Japanese car maker said one of its cars had failed fuel tests.
The company said it would hold a news conference in Tokyo at 5pm local time (08:00 GMT) about the issue.
Tetsuro Aikawa, president of Mitsubishi Motors, will attend the briefing.
Shares closed down 131 yen at 733 yen in Tokyo – their biggest one-day fall in nearly 12 years.
“One of our models was found to have failed part of a fuel economy test,” a spokesman said.
In 2014 South Korean car makers Hyundai and its affiliate, Kia, agreed to pay $350m in US penalties for overstating their vehicles’ fuel economy ratings. They also resolved claims from car owners.
The Mitsubishi revelation follows last year’s emissions scandal at Volkswagen in which the German car maker was found to have installed devices in some models that fooled tests.
VW is recalling millions of cars worldwide as a result of the scandal and has set aside €6.7bn (£4.8bn) to cover costs.
It resulted in the company posting its first quarterly loss for 15 years of €2.5bn in late October.
Source: BBC