Dishwasher interior remains cold throughout the cycle and cleaning is poor, but no heating error code is shown.

Safety first: Unplug the dishwasher before testing the heater circuit.

• Confirm temperature: Open the door mid-cycle and feel the water. If consistently lukewarm or cold, suspect heating issues.
• Test heater resistance: Access the heater terminals and measure resistance. Compare with Iberna specifications; a significantly higher resistance than normal can reduce heating.
• Check NTC readings: Measure NTC resistance at room temperature and in warm water. If readings are outside expected range, replace the NTC.
• Inspect relay contacts: On the control board, check the heater relay for pitting or poor solder joints. Replace the board if the relay is unreliable.

Restoring proper heating will improve both cleaning and drying performance.