JAPANESE authorities are to investigate 19 marine engine makers for potential manipulation of nitrogen oxide (NOx) emissions data in engine tests, after prominent manufacturers Hitachi Zosen and IHI admitted wrongdoing.

Japan's Financial Services Agency, its banking regulator, will request a report from the 19 engine makers by the end of September to determine whether they engaged in any wrongdoing regarding fuel consumption data on marine engines, the Japanese Ministry of Land, Infrastructure and Transport said in a press release.

 Hitachi Zosen said on July 8 following an internal investigation that it had falsified fuel consumption testing data for 1,363 vessels.

The company, a licensee of major two-stroke main engine designers WinGD and MAN for Japan, said the falsified data “possibly impacted” the calculation of nitrogen oxide (NOx) emissions.

Hitachi Zosen's internal investigation found fuel consumption data was “altered” at the time of trials to be kept within the permissible range required in their customer’s specification.

“We believe that this matter stems from a lack of awareness regarding compliance,” the company said.

It reported no cases that might raise questions about the safety of the engines in question during test operation and actual use.

Hitachi Zosen's announcement came a month after another Japanese engine maker IHI had admitted manipulating engine emissions data on 4,751 marine engines out of 5,333 it delivered since 2003. Japanese authorities inspected IHI's engine manufacturing plants at which the data rigging occurred after the misconduct was revealed, according to local media.

Hitachi Zosen will establish a special investigation unit comprising of external experts to propose measures to prevent recurrence of such altering of data, after completing an investigation into the causes of the incident.

The falsified test results affected engines built by Hitachi Zosen Marine Engine and Imex, while the two companies issued NOx emission verifications for 39 different engine types. Hitachi Zosen Corp owns a 65% stake in Hitachi Zosen Marine Engine, while Japanese shipbuilder Imabari owns 35%. Imex is fully owned by Hitachi Zosen Corp.

The company said it was still trying to verify whether the falsified data amounted to any violations of laws and regulations.

Classification society Class NK issued certificates of Engine International Air Pollution Prevention (EIAPP) to 67 of the vessels, Hitachi Zosen said.

Leading two-stroke engine designer MAN has 10 licensees in Japan, while its competitor WinGD has three. 

In an emailed statement, MAN said it was made aware of this issue on July 5, 2024. “We will continue our discussions with both companies to learn more about the situation,” MAN said.

WinGD and Class NK were approached for comment.

The International Maritime Organization has three tiers of NOx emission limits depending on a vessel’s keel laying date that forms its construction date in the eyes of the IMO. There have been calls to change this parameter, as shipowners in the past have dodged this rule by laying the keel earlier, but not building the rest of the ship until much later. Norway will start using a new criteria for vessels' newbuilding dates in its upcoming Emissions Control Area (ECA) in the Norwegian Sea to close that loophole. 

Vessels operating in the upcoming Norwegian Sea ECA will adhere to the three date criteria, meaning three different building dates will be considered for vessels that must comply with Tier III NOx limits.

The IMO’s NOx regulations rely on EIAPP certificates that must be approved by the flag state.