Japanese carmaker Subaru has been manipulating data on fuel economy exhaust gas emissions for a number of its vehicles for many years. Here, the Subaru logo is seen at the New York Auto Show in the Manhattan borough of New York City, March 28, 2018. REUTERS/Brendan McDermid

Japanese carmaker Subaru is in another inspections-related controversy for the second time in less than a year, following reports Thursday in Japanese media that said the manufacturer of Outback and Forester SUVs was found to have been altering inspections data for fuel economy and emissions.

According to reports, the tampering of data had been going for a number of years at a Subaru plant near Tokyo, and that the data was for a number of vehicle models, including the Forester. There were hundreds of instances of data manipulation, which was being done regularly and involved numerous inspectors.

Following instructions from Japan’s transport ministry, Subaru is conducting an investigation to determine exactly when the data falsification began, and why, and will submit a report in the coming week. The company will also have to implement a mechanism to assure ministry officials that such malpractice, thought to be systematic, would not be repeated.

The alteration of data took place at a Subaru factory in Ota, a city in Gunma Prefecture, about 60 miles north of Tokyo. The same plant was in news in October 2017, when it was revealed unqualified employees had been carrying out the final inspections of vehicles before they left the facility.

Following its admission in October, Subaru recalled 255,000 vehicles in Japan, and soon increased that number to about 400,000 cars. All those vehicles were inspected again by qualified employees, and the recalls were restricted to Japan. In the beginning of March, Subaru announced its president, Yasuyuki Yoshinaga, would step down from his position and the board would be revamped as well.

It is not yet known if this new scandal will affect vehicles that were sold overseas. Subaru’s biggest market is the United States, where it has seen slowing sales.

Several other Japanese carmakers with significant operations in the U.S. have been embroiled in similar scandals in the recent past. Nissan had admitted twice to unqualified inspectors looking at final checks, the second time in October. In 2016, Mitsubishi and Suzuki had agreed to being guilty of exaggerating fuel economy of their vehicles by cheating on tests.

The falsification of data on exhaust gases by Subaru is similar to the incident that dogged Volkswagen, but the German auto manufacturer produces a lot more vehicles than Subaru, and therefore that scandal was at a much larger scale. The extent of the Subaru scandal would perhaps become clear only when the company submits its report to Japan’s transport ministry.

Shares of Subaru took a hit during Thursday trade on the Tokyo stock exchange, underperforming the rest of the auto sector. At 1:23 p.m. local time (12:43 a.m. EDT), Subaru shares were trading 2.19 percent lower, while competitors like Toyota, Mazda and Nissan were all in the positive territory.