[6] Polish State Railways then ended orders for new rolling stock, including electric multiple units.

This allowed Polish manufacturers and carriers to gain experience in the production and operation of lightweight rolling stock.

[8] At the beginning of the 21st century, electric traction units from new manufacturers, such as Pesa Bydgoszcz, Newag, and Stadler, began to appear on Polish tracks.

[9] Pesa, after a deep restructuring in 1998, started producing railbuses in 2001, but in 2004, it also undertook the construction of the first electric multiple unit[10] – the 13WE (EN95) for the Warsaw Commuter Railway, adapted to a 600 V DC.

[11] In 2005, the Marshal's Office of the Łódź Voivodeship[12] announced a tender for the delivery of a three-car electric multiple unit.

[16] Marek Adamczewski [pl], Jacek Poćwiardowski, Jakub Gołębiewski, Mariusz Gorczyński, and Barbara Kusz-Hallmann were involved in the train's design.

In September, Marad Design and Pesa presented the results of their work to the client after negotiations, and they began creating the final project.

[13] On 1 April 2006, the vehicle was completed, and its first trial run took place on the route from Bydgoszcz Główna to Laskowice Pomorskie [pl].

[12] On April 3, the vehicle reached a speed of 120 km/h on the same route,[19] and two days later, the train traveled to the Railway Institute test track in Węglewo near Żmigród.

[20] On May 30, the Rail Transport Office [pl] issued approval for the vehicle's operation in both the three-car and four-car versions.

[27][28] The electric multiple unit type 15WE is a three-car, single-deck train designed for regional passenger services on electrified lines powered by 3,000 V DC.

[13] The entrance doors are equipped with individual opening buttons activated after unlocking by the driver and closing signal.

In addition, the interior of the unit is equipped with a visual and voice information system, 10 monitoring cameras, and smoke detectors.

This data is also stored by a digital parameter recorder in the internal memory, which can be read and analyzed on an external computer.

Each motor is powered by an individual three-phase traction inverter type FT500-3000 produced by Medcom [pl] using IGBT technology.

[13] On 29 May 2006, the Acatus was ceremonially handed over to the Przewozy Regionalne company, after which the unit was deployed to operate routes in its home voivodeship.

[13] In the second half of 2011, the unit was parked at the base of the Łódź Regional Transport Company in Idzikowice [pl] due to a lack of overhaul repair.

In June, it was announced that the repair would last until July, but again, it did not materialize due to prolonged negotiations regarding the terms and scope of the overhaul.

[13] In December 2013, the vehicle was sent to the manufacturer's facility for repair,[32] during which it was repainted in the new colors of the Łódź Voivodeship and equipped with Wi-Fi and ticket machines.

In July 2017, the procedure was still ongoing, and the Łódź Voivodeship marshal's office announced that the work leading to the issuance of a new document was advanced.

[36] On 2 April 2020, the Łódź Voivodeship Board made a resolution regarding the sale of the ED59-01,[37] and in May 2021, the media reported that the vehicle had been repurchased by the manufacturer.