A combination of a twine tensioner arm (172, 252) and arm position sensor arrangement (200, 250) for a large square baler (300) is disclosed. The combination comprises said twine tensioner arm (172, 252) having front and rear ends and being mounted to a frame (112) at a front end region establishing a connection permitting said tensioner arm (172, 252) to be moved between upper and lower extreme positions and said tensioner arm (172, 252) being biased to said upper extreme position and having a twine guide (186, 268) at its rear end for being engaged by a twine strand (62a - 62f), which, when tensioned during bale formation, moves said tensioner arm (172, 252) toward said lower extreme position. Said arm position sensor arrangement (200, 250) including a rotary potentiometer (210, 236) having a rotatable sensing shaft (224), a follower arm (228, 272) having a first end coupled to said rotatable sensing shaft (224) and having a separate end located in a path of movement of the twine tensioner arm (172, 252) for being engaged by, and moved together with, the tensioner arm (172, 252) as it moves between said upper and lower extreme positions, with the potentiometer (210, 236) generating an electrical signal representative of the position of the tensioner arm (172, 252) at any given time. Further a large square baler (300) with such a combination is disclosed.