Miele Dishwasher Error Code F78 — Circulation Pump Relay Fault
What this means
Error F78 on Miele dishwashers indicates the control board has detected an abnormal condition in the relay or triac circuit that controls the circulation pump. The pump may not start, or it may start and not stop, or the board detects current flowing when the pump should be off. This is typically a control board-level fault rather than a pump motor issue.
Alternate codes: F 78
Step-by-step fix
4 stepsPower-cycle the dishwasher
Turn off power at the breaker for 10 minutes. Restore power and attempt a cycle. A relay may have been stuck due to a momentary overload and may reset.
If the pump runs immediately when power is restored (before any button is pressed), the relay is stuck closed — turn off power immediately.
Check if the pump runs independently
Start a cycle and listen for the circulation pump. If F78 appears and the pump makes no sound, the relay may be stuck open. If the pump runs non-stop even when the cycle ends, the relay is stuck closed.
A relay stuck in the closed position is a safety concern — the pump running continuously can overheat.
Inspect the control board
Unplug the dishwasher and access the main control board. Look for burned or blackened areas near the relay components. Also check for bulging or leaking capacitors near the relay circuit.
The pump relay is usually one of the larger components on the board. It may be visually identifiable by burn marks.
Consider control board replacement
F78 almost always requires control board replacement. While a skilled electronics technician could potentially replace just the relay, Miele boards are complex multilayer PCBs and component-level repair is risky.
Ensure you order the correct board for your specific model number and production date.
When to call a professional
F78 is typically a professional-only repair. The control board needs to be replaced and may require programming or configuration by a Miele-certified technician.
Related error codes
Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.
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