Error code E91 appears, dirt or deposits on titanium plates, lower / no salinity, cell cable loose, cells defective?

1. Remove the electrolytic cell for inspection and cleaning if necessary.
2. Use salinity test strips to check the value of the water.
   Add salt. See "Salinity Information".
3. Make sure that the cable of the cell is firmly plugged into the socket.
4. If necessary, replace the cell.