Dishwasher does not heat water; cycle runs long and ends with E3

Safety first: Disconnect mains power and ensure the machine is cool and empty before working on it.

• Check for obvious signs: Run a short cycle and open the door mid-cycle (carefully) to see if water is warm. If always cold and E3 appears, suspect the heater circuit.
• Access the heater: On many De Dietrich dishwashers, the heater is integrated in the circulation pump assembly under the tub. Lay the machine on its back (with towels) and remove the bottom panel to access the pump/heater unit.
• Test heater resistance: Disconnect the heater terminals and measure resistance with a multimeter. Typical values are 20–30 Ω. Infinite resistance indicates a failed heater.
• Check NTC sensor: Locate the NTC (temperature sensor) on the sump or heater body. Measure its resistance at room temperature and compare with service data (commonly 50–100 kΩ). If open or shorted, replace.
• Inspect wiring and board: Look for burnt connectors or tracks on the control board near the heater relay. If the relay is visibly damaged or the board smells burnt, the board may need professional repair or replacement.