Ayce C2065A Manuel D'utilisation page 92

INDOOR
5.
If the wireless sensor's signal has discontinued and does not recover
within 1 hour, the signal icon will disappear. The temperature and
humidity will display "Er" for the corresponding channel.
6.
If the signal does not recover within 48 hours, the "Er" display will
become permanent. You need to replace the batteries of the "Er"
channel's sensors and then press [ SENSOR ] key to pair up with the
sensors per each " Er" channel again. (For CH 4~6, you need to show
the channel on the LCD screen first and then repeat the pairing
process.)
Note:
You need to press [ SENSOR ] key to manually receive the sensor's
signal after you've placed the new batteries to the wireless sensor, or
the main unit fail to receive the wireless sensor's signal.
ALERT SETTING AND DISPLAY
The unit can set up multiple temperature and humidity HI/LO alert for
indoor and up to 8 outdoor channels.
CHANNEL 6
Signal discontinued
CHANNEL 8
GB