TOKYO (Reuters) - Nissan Motor Co 7201.T said on Wednesday an "extremely low awareness" of the seriousness of inspection standards and rules had led to improper measuring of exhaust emissions and fuel economy in vehicle models made in Japan.

FILE PHOTO: The logo of Nissan Motor Co is pictured at a showroom at the carmaker's headquarters in Yokohama, Japan May 11, 2017. REUTERS/Toru Hanai/File Photo

Nissan said in July that sample testing for emissions and fuel economy in final vehicle inspections at most of its factories in Japan did not meet domestic standards, the second case in less than a year where misconduct was found in its inspection process.

The Nissan case is the latest incident of data tampering which has tarnished Japan’s manufacturing industry and its reputation for high-quality, efficient production.

Nissan, Japan’s second largest automaker, said the breach of inspection standards was similar to a case last year, when the firm admitted that for decades uncertified inspectors had signed off on final checks for cars sold in Japan.

“As a company - executives, managers to plant supervisors - Nissan had extremely low awareness of the gravity of violating (final vehicle inspection) standards and rules,” Nissan said in a statement.

It blamed the misconduct on a shortage of final inspectors and a lack of oversight by plant managers, the automaker said, adding it also needed to do more training.

Nissan said there were improper inspections during sample testing of 1,205 vehicles, more than the 1,171 units the company had initially reported in July.

Other tests for horn volume, external vehicle noise and the aim of headlights were also conducted improperly, Nissan said.

The testing was for vehicles destined for the Japanese market and did not affect units exported overseas, the automaker has said.

Nissan said its sample tests would now be overseen by supervisors and managers. It also planned to boost the number of inspectors and revamp the computer software used to measure vehicle emissions.

Separately, Suzuki Motor Corp 7269.T said on Wednesday it found that 6,438 vehicles had been improperly tested for emissions and fuel economy, slightly higher than what the company reported to the government in August.

Last month, Suzuki Motor, Mazda Motor Corp 7261.T and Yamaha Motor Co 7272.T apologised for improper testing, but said they did not find significant problems with the actual emissions and fuel economy of their vehicles to be sold in Japan and did not plan any recalls.