Dishwasher displays F4; unit may not heat water properly and cleaning performance is reduced.

Safety first: Turn off power at the breaker. Allow the dishwasher to cool before working near the heater.

• Confirm lack of heat: Run a heated cycle and check if the tub and dishes are warm at the end. If cold and F4 appears, suspect heater issues.
• Inspect heater: Remove the lower rack and visually inspect the heater element for breaks or burn marks.
• Access heater and thermostat: Pull the dishwasher out and remove the bottom panel. Locate the heater terminals and any inline high-limit thermostat.
• Test continuity: With a multimeter, check continuity across the heater and thermostat. Replace any component that tests open.
• Check wiring: Inspect heater wiring for burns, loose connections, or damage. Repair or replace as needed.
• If components test good: The control board heater relay may be defective. Replacement of the control is typically required and best done by a technician.