Miele T4262 “Empty Container” Warning

I have a Miele T4262 Condensing dryer and I suspect the “Empty Container” warning doesn’t work.

I say this because despite my constant nagging the kids often forget to empty it resulting in the heater element getting damp and tripping our RCD, I then have to remove the heater and dry it which is a pain!

Can anyone please tell me how the machine knows when the container is full and where the full sensor is located?

Thanks!