If you have paired the sensor to the wrong slot on the display (i.e overwriting [T1 SENSOR] when you did not mean to) you can un-pair it and re-pair it again.
You will need to do this on both the temperature sensor and the corresponding pairing slot on the display.
1. Firstly to remove it from the display enter the “Pair” menu (press and hold in the “-“ and “+” buttons together) and cycle through with the “+” button to the corresponding slot (e.g [T1 SENSOR]).
2. Hold the middle button on the display until [CONN] changes to [NONE].
3. Squeeze the two clips on each side of the temperature sensor and slide the cover off.
4. Press and hold the pairing button for 8-10 seconds or until the red LED flashes start to flash in quick succession.
The temperature senor is now ready to pair to a new pairing slot on the display.