The A6142 is a loop off the A58 to the east of the Yorkshire town of Sowerby Bridge. The road was originally numbered B6140 and gained its present number in the 1960s. The road is steeper than the A58 but shorter which may explain why that road has the route it does. However, through traffic on the A58 is now directed along the A6142, hence the Class I status for the road.
The road starts at a mini-roundabout on the A58 Bolton Brow, as that road climbs out of the valley of the River Calder. The A6142 heads east along Pye Nest Road, a street name it keeps for its entire length. The road begins by climbing steeply, then becomes residential as the gradient lessens. Presently the road bends round to the left and becomes steeper once more as it climbs back up to the A58, ending on that road at a T-junction.