Article reference KA-01822
This is an error and could be caused by a defect in the display, or main PCB or the wire connecting the two together.
This will require a service visit with the below spare parts -
170L cylinder display & cable = 500002222
200 & 270L cylinder display & cable = X-B4992570
Main PCB (all 3 sizes) = X-B1244096
Note: It is impossible to ask for the backup to run if there is a display or comms cable fault as the hot water cylinder cannot energise the immersion element, if it cannot reliably control it from the screen/PCB.
Applicable Models:
EDL170-520, EDL170-520RF, EDL200UK-630, EDL200UK-630RF, EDL270UK-630, EDL270UK-630RF