Below are the error messages that can appear on you S40 controller. You will also find instructions on how to resolve the error: 

ER3: Run dry protection. If this happens -

1. First unplug,
2. Now press the reset button on the bottom centre of the unit,
3. Fill with water and plug back in.

ER4: Thermostat overheating protection. This can happen when the heating element and thermostat are covered by a hop or grain bag, trapping the high heat of the element in a small area right next to the thermostat. Do not use large hop or grain bags in the Mash and Boil, as they obstruct heat circulation and cause this error.  It can also be caused by heavy trub deposits resulting from too fine a grain crush, or malt extract or honey being poured into the unit, coating the thermostat and the heat element -

1. Clear the obstruction
2. Reset by unplugging, and pressing the reset button on the bottom centre of the unit.

ER5: Too high a temperature -

1. Unplug
2. Let cool
3. Press reset button on the bottom centre of the unit.