Dishwasher stops and shows F3, water may be cold and dishes are not cleaned properly.

Safety first: Unplug the appliance and ensure it cannot be switched on accidentally. Heating components carry mains voltage.

• Check water temperature: Run a short program and carefully open the door mid-cycle (after 10–15 minutes). If the water is cold, the heater is not operating.
• Inspect wiring: Remove the lower kick panel and side panels (if accessible) to visually inspect the wiring harness to the flow-through heater and NTC sensor for burns, loose connectors, or corrosion.
• Test heater resistance: With the dishwasher unplugged, disconnect the heater terminals and measure resistance with a multimeter. A typical Bauknecht flow-through heater is usually between 20–30 Ω. Infinite or zero resistance indicates a faulty heater.
• Check NTC sensor: Locate the NTC (often clipped into the sump or heater housing) and measure its resistance at room temperature; compare with service data if available. A shorted or open sensor will trigger F3.
• Control board: If heater and NTC test good, the heater relay on the main control module may be defective. Board repair or replacement is usually a technician-level job.