During the renewal of the locomotive, the old engine was completely replaced, since such engines are no longer manufactured. They were designed back in the 40s of the last century, primarily for German submarines of the World War II.

Instead of the old engine, a modern American-made diesel Caterpillar was installed. It belongs to the latest generation of Caterpillar diesel engines, certified for harmful emissions according to the Stage V standard. Thus, the Promet FAU 52 is now one of the most environmentally friendly locomotives in Europe.

New engine characteristics:

· power – 650 horsepower

· fuel consumption while idling - 1.3 liters per hour (12 times less vs. the old engine)

· harmful emissions into the atmosphere are reduced by 15 times

In addition to replacing the engine, the cabin of the locomotive was modernized for the maximum comfort of drivers. The new cabin is designed taking into account modern requirements for workplace ergonomics. It is equipped with air conditioners, modern controllers have been installed on the control panels, which makes the equipment more convenient and attractive for the young generation of Promet Steel railway workers.

The company allocated around USD 500,000 for the overhaul of the locomotive. All works were carried out in Bulgaria (city of Ruse). In December 2022, the locomotive was delivered to Promet Steel, where pre-commissioning and commissioning works were carried out and drivers and members of locomotive crews were trained.