The class 03 steam locomotives were actually an emergency solution to the existing class 01 units. The DRG's program of locomotive types from 1923/24 had only planned the class 01 with its 20 ton axle load as a standard design express locomotive. The bad financial condition of the DRG however did not permit quick rebuilding of lines to 20 ton standards, so that by the end of the Twenties no class 01 units could be used, particularly in the North German districts. Older provincial railroad locomotives were also not suitable, because many lines were only rated for an axle load of 17 tons. So, a "lightweight express locomotive" was ordered from the locomotive builders with a maximum axle load of 17.5 tons which then appeared for the first time starting in 1930 as the 03 with three pre-production locomotives delivered from Borsig. They were followed by another 295 units by 1937. In addition to Borsig, Krupp, Henschel, and BMAG were also involved in building the locomotive.
The boiler and cylinders were smaller than on the 01; the bar frame was also lighter so that the locomotive had a wheel set running weight of a maximum of 18 tons. Starting with road number 03 123 the pumps were moved to the middle of the locomotive and from road number 03 163 on the locomotives had larger pilot wheels. In 1934, road number 03 154 was given streamlined cladding as an experiment. In 1936, road number 03 193 was also given complete streamlining as an experiment; this unit was kept in reserve at the same time in case the class 05 was out of service.
These locomotives were preferred in Northern and Eastern Germany where numerous main lines were still not rated for 20 ton axle loads. After World War II, 86 units went to the DR in East Germany, 144 were acquired by the DB, and the rest went to the PKP (Polish State Railways) or remained missing. The DB units were stationed in Osnabrück, Hannover, Mönchengladbach, and Trier among other places and from 1960/61 on at the district in Rheine, the stronghold of the class 03. At the end of the Sixties the 03 (from 1968 on: 003) was superfluous. The last DB units were used by the Ulm District until 1972 on the main line to Friedrichshafen.