The disclosure relates to a sensor arrangement for an injection device to determine an axial position of at least one device component of the injection device inside a housing of the injection device. The sensor arrangement includes an elongated member located inside the housing, extending in an axial direction and having at least a first section and a second section of different magnetization. The first and second sections are separated in an axial direction. The sensor arrangement also includes at least one magnetic sensor element attached to the housing to detect the axial position of at least one of the first and second sections.