Article reference KA-01566
The LCD has an inbuilt temperature sensor and if it detects it has seen an excessive temperature.
This could occur if the heater is covered or obstructed.
It could also occur if the storage elements were not inserted correctly into the core when the heater was installed, or if the inner core cover is not correctly secured and the insulation correctly tucked in correctly.
If none of these are the issue, it could be a faulty temperature sensor inside the User Interface screen – the solution is to replace the User Interface.