Dishwasher fills but water does not heat; cycles run cold and E3 appears on the display.

Safety first: Isolate the dishwasher from mains power. Heating components operate at high voltage.

• Confirm symptom: Start a wash cycle and feel the door or tank exterior after several minutes (without opening the door). If it remains cold and E3 appears, proceed with checks.
• Inspect wiring: Remove the lower front or side panel to access the tank heater terminals. Look for burnt connectors, loose spades, or discoloured wiring and repair or replace as needed.
• Test heating element: With power off and wires removed from the element, use a multimeter to measure resistance across the heater terminals. An open circuit indicates a failed element that must be replaced.
• Check for earth leakage: Measure resistance between each heater terminal and earth; a low reading suggests insulation failure and the heater should be replaced.
• Check temperature probe: Locate the NTC sensor on the tank or hydraulic circuit. Inspect for scale buildup and clean gently. Test resistance at room temperature and compare with Comenda specifications; a short or open circuit indicates a faulty probe.
• Control components: If heater and NTC test correctly, the heating relay/contactor or control board may be defective and should be evaluated by a professional.

Do not bypass safety thermostats or relays. Replace faulty components with genuine Comenda parts.