Toyota confirmed and immediately apologized for the fraudulent evaluation of its diesel engines, writes The Register.

The day before, Japan’s Ministry of Land, Infrastructure, Transport and Tourism published the results of an investigation that showed that the software used to control the test engine had been illegally rewritten to incorrectly calculate engine performance.

Prior to the agency’s investigation, the company also found irregularities in the power testing process for which the engine control units were used. This software was different from the software used in mass production.

This resulted in erroneous and sometimes overestimated results.

At the end of January, Toyota also stopped supplying cars with engines whose performance was calculated incorrectly.

The Ministry identified three such engines: 1GD 2.8-liter turbo diesel with four cylinders, 2GD 2.4-liter turbo diesel with four cylinders, and F33A 3.3-liter twin-turbocharged V6 diesel.

The ministry gave the company a month to correct the error and also forced it to change its work culture so that employees could report such problems more quickly and comfortably.