Dishwasher fills but does not heat; cycle runs unusually long and ends with E3.

Safety first: Disconnect mains power. The heater circuit operates at full line voltage and can cause severe shock.

• Confirm symptom: Run a short hot program and open the door mid-cycle (after 15–20 minutes). If the water is cold and E3 appears, proceed with heater checks.
• Access heater: Remove the lower kick panel and, if necessary, tilt the dishwasher carefully to access the flow-through heater mounted on the circulation pump or in the base.
• Test heater resistance: Disconnect heater connectors and measure resistance with a multimeter. Compare to Ilve specifications (typically 20–30 Ω; check service manual). Infinite resistance indicates a failed heater.
• Inspect wiring and connectors: Look for burnt or loose spade terminals on the heater and at the control module.
• Check NTC sensor: Locate the NTC temperature sensor in the sump or on the heater housing. Measure its resistance at room temperature and compare to spec. A shorted or open NTC can trigger E3.
• If heater and NTC are OK: The heater relay on the main control board may be defective. Visual inspection may show burn marks; replacement of the control module is usually required.