Nissan admitted Monday that data on exhaust emissions and fuel economy had been deliberately "altered", dealing a blow to the Japanese car giant's efforts to recover from an inspection scandal last year.
The company did not say how many cars were affected by the falsifications, which were uncovered during voluntary tests of all parts of Nissan's operations conducted in the wake of last year's scandal.
It said that tests on exhaust emissions and fuel economy had "deviated from the prescribed testing environment".
In addition, it said inspection reports had been drawn up "based on altered measurement values".
Nissan's share price dropped 4.56 percent to 1,003.5 yen after it said it would make a statement on exhaust measurements following a report of falsification.
The firm vowed a "full and comprehensive investigation" into its latest fake data scandal.