tunze 5017 help

[hani]

my 5017 not working water level was too low but the sensor reading as its on level, turned it on and off but nothing going on it seems the sensor not reading right, the unit is about 3-4 years old? any thought
thanks

 

[rvitko]

I would first try soaking the optic sensor in vinegar for a few hours, if that does not solve it, the sensor can be replaced.