However I recently added a UV detector from OS and found its RF connection was decidely flakey. It is a well built device and taking it apart was somewhat difficult, but I managed it. After numerous checks and trials of the internals over a number of weeks I concluded the spring wound internal antenna in the sensor housing was made of very stiff wire and had very little give in it. Once I had removed it and replaced it with a 170mm length of hookup wire that exited out of the lower side of the housing, the connection was perfect and quite robust.
The antenna was glued to the body of the sensor and the RF board inside the sensor was screwed to a pannel held in by more screws. My guess is the antenna's conection to the PCB was too rigid had broken the copper track off. As a result it had become an intermittent connection. That is, worked when I had played with it, and gone bad with the hot and cold of outside temperatures.
So just to contradict myself above, sometimes it is the 433MHz connection that needs to be investigated.
Also look up my GitHUB Site for more infor on how to design your own sensors, and add an RGB LED for a status indicator. Very handy for debugging any connection problems, hardware or software.
Cheers, Rob