Photo/IllutrationNissan Motor Co. Chief Competitive Officer Yasuhiro Yamauchi, left, apologizes on the latest scandal in a news conference in Yokohama on July 9. (Naoko Kawamura)

Nissan Motor Co. acknowledged that exhaust emission and fuel economy values were falsified in post-production tests for its cars sold in the domestic market, the second scandal involving the automaker in less than a year.

The Yokohama-based company said July 9 that measurement values were altered at five of its six plants during final vehicle inspections involving 1,171 cars.

It said the 10 employees responsible had acted without their superiors' knowledge, adding that data for 19 models in the Nissan lineup, among them the Note, Skyline and March brands, had been tampered with since 2013.

Last year, the company disclosed that unauthorized personnel conducted final inspections on cars sold in Japan.

The transport ministry slapped Nissan with business improvement orders last September and again in March.

The latest scandal involved checks on cars prior to shipment to dealers in Japan.

For the tests, workers randomly pick one in every 100 completed cars to check exhaust gas emissions and fuel economy. The tests are needed to confirm that car makers are manufacturing their vehicles to the performance levels reported to the government. The results, in turn, become basis for the government’s certification.

Measurement values were altered at Nissan's Tochigi plant in Tochigi Prefecture; Oppama plant in Kanagawa Prefecture; the Nissan Shatai Kyushu plant in Fukuoka Prefecture; the Nissan Shatai Shonan plant in Kanagawa Prefecture; and the Auto Works Kyoto plant in Kyoto Prefecture.

Those responsible also altered figures on humidity and other conditions that prevailed during the tests when they did not meet the official criteria.

Similar alterations occurred at car maker Subaru Corp. In response to the finding, Nissan carried out its own investigations and discovered the matter in June.

The 1,171 cars accounted for 53.5 percent of the 2,187 units whose data was available.

In a news conference held in Yokohama on July 9, Nissan's chief competitive officer, Yasuhiro Yamauchi, apologized for the latest scandal.

He and other executives said it appeared that those responsible had not thought that tweaking the measurement values would cause significant problems.

If measurement values deviate from the reported performances, shipments are stopped.

The differences detected in the latest case were not enough to conflict with listed performance data.

"We’re sorry that this matter has come to light when we were proceeding with steps to prevent a recurrence (of unauthorized personnel carrying out tests),” Yamauchi said.

Nissan said it will flesh out details of the latest scandal by entrusting an outside law office to investigate the matter. The company expects to announce the details in about a month or so.

(This article was written by Yoshitaka Ito and Satoshi Kimura.)