Dishwasher displays F3 and will not complete the wash; often stops during heating phase.

Safety: Disconnect power at the breaker. Do not work on the heater circuit with power connected.

• Run a hot water test: Before starting the dishwasher, run the kitchen tap until water is hot. This reduces heating time and can help confirm if the heater is working at all.
• Check for obvious wiring damage: Remove the lower front panel and inspect the wiring harness going to the heater assembly (often integrated into the Asko circulation pump or located in the sump). Look for burned connectors or melted insulation.
• Test the heater element: With power disconnected and wires removed from the heater terminals, use a multimeter to measure resistance. A typical Asko dishwasher heater is usually between 20–40 ohms. Infinite resistance indicates a failed heater.
• Inspect the NTC sensor: The temperature sensor (NTC) is usually mounted in the sump. Check its connector for corrosion. If you have a multimeter, measure its resistance at room temperature and compare with Asko specifications (often around 50kΩ at 25°C, but verify for your model).
• If heater and NTC test good: The main control board heater relay may be defective. Control board replacement is complex and generally recommended for a professional technician.