DIAGNOSIS "ERR" is a generic fault for a communication error between the main control board and the user interface panel or a sensor reading outside expected range during a mode change.
FIX The first step is always a hard reset. Unplug the unit from the wall outlet. Wait two full minutes. While unplugged, press and hold the POWER button on the unit for 10 seconds to discharge any residual power. Plug it back in. This clears the temporary error state in 90% of cases.
IF THAT DIDN'T WORK The error may be triggered by rapidly turning the selection dial or pressing buttons before the previous command is processed. Always allow the display to fully update after each input. Operate controls deliberately, with a one-second pause between selections.
HEADS UP If "ERR" appears consistently when selecting a specific function like Bake or Dehydrate, the internal heating element or fan for that circuit may have failed, requiring service.