Chairman Akio Toyoda will hold a news conference at 0800 GMT on Monday, the company said.
The transport ministry said separately it will conduct an on-site inspection at Toyota's headquarters on Tuesday after saying irregularities were found in model applications from Toyota, Mazda Motor, Yamaha Motor, Honda Motor and Suzuki Motor.
The ministry said it would take strict measures based on its investigation and that it had ordered three companies to suspend shipments of some vehicles.
Toyota said it temporarily halted shipments and sales of three car models made in Japan.
A Toyota spokesperson added that the company is still investigating issues related to vehicle fuel efficiency and emissions, and aimed to complete the inquiry by the end of June.
The company's shares dropped, falling as much as 2.3% in afternoon trading in Tokyo.
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