[7] At that time, Polish State Railways ended orders for new rolling stock, including electric multiple units.

[9] In the early 21st century, new manufacturers like Pesa Bydgoszcz, Newag, and Stadler began to appear on Polish railways with their electric multiple units.

[10] Following a deep restructuring between 1998 and 2000, Pesa, then still known as Zakłady Naprawcze Taboru Kolejowego w Bydgoszczy, started producing railbuses in January 2001.

[3] Therefore, on 25 April 2003, the Masovian Voivodeship government announced an open tender for the delivery of one electric multiple unit for this operator.

Ten rolling stock manufacturers requested the tender documentation, and by June 5, only Pesa and Poznań Railway Repair Plant [pl] submitted their bids.

[16] The main designers were Marek Adamczewski [pl], Magdalena Berlińska, and Jarosław Szymański,[17] supported by Jakub Gołębiewski, Mariusz Gorczyński, Agnieszka John, Tomasz Kozioróg, Emilia Lebiedź, and Jacek Poćwiardowski.

Before the actual train production began,[16] a 1:1 scale mock-up of the final front end was created[16] at the design studio of the Gdańsk Academy of Fine Arts.

[29] The manufacturer claimed that it was possible to build Mazovia adapted to any power supply voltage,[25] but no other orders for such a vehicle were placed, and ultimately, only one unit was produced for the Warsaw Commuter Railway.

[12] In 2005, Pesa, using the experience from building the 13WE unit and its solutions, constructed the first Polish electric motor coach type 308B [pl].

The new vehicle had identical front walls and driver's cabs as the 13WE unit, and the central part with a lowered floor between the bogies was designed in the same way.

The interior is equipped with CCTV, forced-air and electric convective heating, visual and auditory passenger information systems, and ticket validators.

The side members are welded into a closed box section and have forked seats at both ends for mounting rubber-metal spring caps, which serve as the primary suspension.

[34] Initially, the vehicle experienced various malfunctions, including current collector[35] and compressor failures,[12] as well as wiring issues,[36] resulting in less frequent operation.

[39] On November 20, the unit was transferred to PKP Warszawska Kolej Dojazdowa in exchange for the Masovian Voivodeship acquiring shares in Warsaw Commuter Railway worth almost 9.4 million PLN,[40] equivalent to the train's value.

[42] In January 2014, Warsaw Commuter Railway announced a tender for the periodic overhaul and modernization of the unit, primarily to adapt it for 3,000 and 600 V DC power.

Additional modifications included installing track cameras, changing heater power supply, tinting side windows, and sealing the roof.

[33] However, the overhaul faced delays due to challenges in selecting new 3,000 V DC electrical components and ensuring safety, structural integrity, and vehicle clearance.

[52] Eventually, the unit was delivered to Grodzisk Mazowiecki on December 11,[53] and the acceptance process began,[54] which also extended beyond the anticipated timeframe.

After May 28, when the Warsaw Commuter Railway network switched to the new power supply, the unit only performed technical and service runs.