The signal strength can be viewed on the pairing screen. Press - and + buttons at the same time for a few seconds to enter pairing mode: the display will show [PAIRING MODE] for a second then show [MAIN SENSOR]. Press either - or + to cycle through the sensors. If the unit is paired it will show [CONN] and the signal strength will be shown by the signal strength icon at the top left of the display. This will be flashing if it is out of range.