The 43 started on 15th July 1985 with 8 journeys a day using one KC from Clontarf. Initial routing was the opposite way in Swords, it came into the village northbound and back by the bypass (which had just been opened), but this was changed very soon after. There was a weekday service only, but Sunday was introduced within a few months. Housing in Kinsealy had only begun at that stage, there was no need for a bus before then. The first bus in the morning used to leave from the Feltrim Rd roundabout, it did not serve Swords village, as they did not want to filled with Swords people. But they soon discovered that the 43 was giving valuable connections from Swords to Coolock etc and all journeys were extended to the village.

Route 43 of course was used twice before. It was the first DUTC bus to Killester in 1925, replaced by 54 in 1939; and was city to Stillorgan from 1940 to early 1960s.