Three members of the class originally operated in the South Island, mainly on the Main North Line between Christchurch and Picton, while the other two members started life in the North Island. In 1969, all members were transferred to work in the Bay of Plenty area on the lightly laid track there. After the Kaimai Tunnel opened in 1978, all five members were transferred to the South Island for service in the Dunedin area. The class performed sterling service on the hilly Dunedin - Palmerston section of the Main South Line and were used to haul the Inch Valley branch line stone trains due to their full adhesion Co-Co wheel set arrangement. On occasions, members of the class made trips to Invercargill as the roster allocated and were used on the Otago Central Line as far as Ranfurly. They remained in Dunedin until 1984 - 1985, when they went north to Wellington and Napier. In their latter days the DI class was used mainly for shunting duties.
In February 1988, three members of the class were withdrawn. DI 1808 was withdrawn after a flash-over in its main generator, and was dismantled at Hutt Workshops in 1991. DI 1814 was withdrawn due to an unknown reason, while 1837 was withdrawn after throwing a conrod. 1843 was withdrawn in May 1989 after being damaged in a level crossing accident near Otaki.
DI 1104 was originally selected for preservation by the Diesel Traction Group. The DTG eventually led preserved 1102 instead for preservation, being the best one of the fleet. The locomotive is now under restoration at the Ferrymead Heritage Park and will be mainline certified.