The screen will show "-- --" when the main unit lost the connection with the outdoor sensors. There are several reasons for this. Please check:
① The sensor is placed incorrectly.
The senor needs to be placed vertically to get a better antenna transmission. Do not place it in other ways.
② Please check if there are thick obstacles or sources of interference between the main unit and sensor.(home appliances such as heaters, cookers, washing machines, oven or other electronic devices at same signal frequency: 433MHZ)
The RF signal is a straight-line signal, so if the barrier in the middle is too thick, it will cause signal loss. Please avoid using the device in a complex environment. Recommend to use it within 30M.
③ The sensor is placed too low from the groud.
It is highly recommended that you place it at a height above 1.5 meters to get a better signal. If placed too low, it will severely shorten the launch distance.
The station will try to re-connect the outdoor sensor automatically every few minutes when it lost the connection. Therefore, once the outdoor senor is placed in right way, usually it will keep the connection all the time.