Dishwasher fills but water does not heat, cycle runs very long or ends with E3 error.

Safety first: Unplug the Iberna dishwasher or isolate it at the breaker. Heating components operate at mains voltage.

• Confirm symptom: Run a hot program and open the door mid-cycle (after 15–20 minutes). If the water is cold and E3 appears, suspect the heater circuit.
• Inspect wiring: Remove the lower kick plate and side panels if necessary. Locate the flow-through heater assembly (often in-line with the circulation pump). Check all connectors for burning, looseness, or corrosion. Reseat any loose plugs.
• Test heater element: Disconnect the heater terminals and measure resistance with a multimeter. A typical Iberna dishwasher heater is around 20–30 Ω. Infinite resistance indicates an open heater that must be replaced.
• Check NTC sensor: Locate the NTC (temperature sensor) usually clipped into the sump or heater housing. Measure its resistance at room temperature and compare with service data; if reading is open, shorted, or far out of range, replace the NTC.
• Control board relay: If heater and NTC test good, inspect the main control board (behind the control panel or side casing) for a burnt heater relay or damaged tracks. Replace the control board if damage is visible or if it fails continuity tests.

Because this involves live mains circuits, if you are not experienced with electrical testing, contact a professional technician.