Kanadevia's ship-engine units faked fuel data on 1,371 of 1,375 engines shipped since 1999

In July 2024, Kanadevia — the industrial machinery group renamed from Hitachi Zosen in 2023 — discovered that two engine subsidiaries, Hitachi Zosen Marine Engine in Kumamoto and IMEX in Hiroshima, had been rewriting fuel-consumption test results on marine engines since 1999. Nearly every engine shipped across that quarter century carried adjusted numbers: an interim report to the transport ministry put it at 1,371 of 1,375 engines, with exhaust-gas readings altered or mis-entered on about 400 more.

The scheme surfaced from outside, not inside. After similar engine-data fraud came out at IHI subsidiaries and Kawasaki Heavy Industries, Japan's transport ministry ordered the whole marine-engine sector to audit itself, and the two subsidiaries' practice fell out of that sweep. Kanadevia's own final report, submitted in December 2024, found 1,335 of the 1,375 engines met nitrogen-oxide rules — but 21 engines may have exceeded NOx limits while customers had been told their numbers were clean.

An external committee of lawyers reporting in March 2025 traced the rot upward. The legal department had learned of the falsification in 2012 and deferred correcting it; by 2015 reports had reached the then-chairman and president, who tolerated the practice; sustained pressure on the shop floor to hit promised fuel figures had made rewriting data routine. President Michi Kuwahara admitted he himself first heard of it in a short private conversation in autumn 2020 — and the company held its first press conference only about eight months after the fraud was confirmed.

1,371 of 1,375 engines shipped since 1999 had falsified fuel data; 21 may exceed NOx limits; chairman leaves board, executives return pay

Delivery pressure: test results were rewritten to match the fuel figures promised to shipowners, so no engine ever 'failed' a test.

Self-certification: the same subsidiaries ran the tests, kept the records and reported the numbers, leaving no independent gate.

Leadership chose silence: reports reached the legal department in 2012 and the chairman and president in 2015, and nothing changed.

No channel for truth: the current president learned of it only in a private chat in 2020 — formal reporting carried reassurance, not facts.

When the team that builds a product also runs its acceptance tests and keeps the records, bad numbers become normal. This fraud took 25 years and a regulator's industry-wide sweep to surface.

Chairman Sadao Mino gave up representative rights in April 2025 and left the board after the June 2025 shareholders meeting. Kanadevia put a Quality Assurance Division directly under the president to supervise group companies' QA departments. The cleanup kept finding more: in February 2025, unqualified welders were found to have worked on 172 bridge jobs; in April 2025, new improprieties surfaced at the Wakasa casting plant, and President Kuwahara plus two directors returned 30% of their monthly pay for two to three months while two auditors returned pay voluntarily.