A whistleblower has sparked the recall of 240,000 vehicles made by Hyundai and Kia.
The employee has revealed some models have faulty parts, including vacuum pipes, fuel hoses and light issues.
The affected models include Hyundai's i-30 hatchback, the Sonata sedan, the Genesis and Kia's Mohave and Carnival minivan.
Kia is a Hyundai affiliate.
"Safety is always Hyundai-Kia's number one priority and we make decisions on recalls or any other customer protection steps in compliance with regulators around the world and stringent internal procedures," the company said in a statement.
Kim Gwang-ho, a 55-year-old Hyundai employee of 25 years, told the BBC he couldn't let it go on any longer. He decided to be the fall-guy as at his age, he had much less to lose than his younger colleaugues.
The two companies have already been ordered to fix 1.5 million cars in South Korea and America over possible engine stalling.