The transport ministry conducted an on-site inspection Thursday of a Kawasaki Heavy Industries plant in Kobe in relation to tampering with test data for ship engines by the company.
Three ministry officials entered the plant at around 9:40 a.m. The raid, based on the marine pollution prevention law, will continue Friday.
The major manufacturer of heavy machinery said Wednesday that fuel economy data was found to have been falsified during test operations for 673 of the 674 ship engines for which manufacturing began in January 2000 and later.
The irregularities were discovered as Kawasaki Heavy checked the engines, subject to nitrogen oxide emission regulations, following a ministry request that covered not only KHI but also many other industry peers.
Kawasaki Heavy inappropriately tweaked testing equipment to keep emissions data within permissible ranges of customer specifications and reduce the variance of data.
The wrongdoing may have impacted the engines' nitrogen oxide emissions, and Kawasaki Heavy plans to investigate whether actual emissions exceeded the regulations and whether data falsification was conducted for engines built before 2000. It also plans to set up a special committee comprising outside experts to look into the cause of the misconduct and draw up measures to prevent a recurrence.
After fuel economy data falsification for ship engines came to light at a subsidiary of IHI and two units of Hitachi Zosen, the transport ministry last month urged 19 other makers of ship engines, including Kawasaki Heavy, to investigate possible data-tampering.
On Wednesday, IHI released the results of its probe over its subsidiary's data tampering. It revised up the number of affected engines built since 2003 from 4,905 to 4,918, and newly identified 1,913 engines with altered data for the period between December 1974 and 2002.