Toyota Motor warned on Thursday of an engine fault affecting eight models of its luxury Lexus and Crown sedans, potentially requiring a global recall that could affect up to 270,000 units.
"The defective engines, whose valve springs are not working properly, may halt in the worst case scenario while driving," Toyota spokesman Hideto Yukawa said. "The company is preparing for taking market measures as soon as possible."
He did not rule out a recall announcement in the future.
The world's largest automaker has been hit by a series of safety recalls and has pulled around 10 million vehicles worldwide since late last year.
Toyota's announcement comes as the company looks to improve its recall process following heavy criticism of the way it handled safety issues in the United States that have been blamed for more than 80 deaths.
The company said that the defective 4.6-litre V8 and 3.5-litre V6 engines had been installed in eight top line models including some hybrids - the Lexus GS350, GS450h, GS460, IS350, LS460, LS600h and LS600hL as well as Crown sedans.
The car maker on Wednesday issued a total of 50,839 recalls in Japan due to faulty airbags and seatbelts in models including Corollas built between 2000 and 2001.
Toyota and rivals Honda, Nissan and Mitsubishi Motors will between them recall more than 100,000 vehicles in Japan because of the issue.
The airbags were made by Tokyo-based parts maker Takata. While no injuries have been reported, the transport ministry warned that the airbag inflator in the passenger seat caused shards to fly out when the airbag opened.
Takata also supplies Audi, Daimler, Chrysler, Ford and General Motors.
The faulty seat belts, which fail to buckle up, were built by Tokai Rika, the ministry said.
Toyota paid a record 16.4-million-dollar fine to settle claims it had hidden gas pedal defects in the United States, and US officials have refused to rule out the possibility of more fines.
The beleaguered auto giant also faces a host of lawsuits over "unintended acceleration" issues that prompted the majority of the recalls, which analysts warn may yet dent the future profitability of the company.