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Error code reference

Miele Dishwasher Error Code F78

Circulation pump fault; interrupted connection between the electronic and the door contact switch or faulty…

Miele codesMiele dishwasher codes

Circulation pump fault; interrupted connection between the electronic and the door contact switch or faulty circulation pump.

First step from the service manual

Check for supply voltage: measure at electronic (SLT) output/input, wiring harness, and circulation pump.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F78 means on a Miele dishwasher

The F78 error code on a Miele dishwasher indicates a circulation pump fault. Specifically, the control electronics have detected either an interrupted connection between the electronic control board (SLT) and the door contact switch, or a failure within the circulation pump itself. The circulation pump is responsible for pushing water through the spray arms during the wash cycle, so any fault in this circuit will halt normal operation and trigger this code.

The diagnostic process begins by measuring supply voltage at three key points: the output and input terminals on the SLT electronic control board, along with the wiring harness connectors and the circulation pump terminals. This systematic voltage check helps isolate whether the fault lies in the control board's ability to send power, a break or short in the wiring harness, or an internal failure of the pump motor itself.

The door contact switch is also implicated in this fault code. An interrupted connection between the electronic board and the door contact switch can prevent the pump from receiving its operating signal, mimicking a pump failure even when the pump motor is mechanically sound. Technicians should inspect the wiring between these components for corrosion, loose pins, or damaged insulation before condemning the pump or the control board.

Source: manufacturer service documentation.

Common causes of F78

  1. 01

    Faulty wiring harness connection

    Wiring / connection

    A broken, corroded, or loose connection in the wiring harness between the SLT control board and the circulation pump is a frequent cause of F78. Inspect all connectors and wire runs for damage, moisture intrusion, or pulled-back pins.

  2. 02

    Failed circulation pump motor

    Part replacement

    The circulation pump motor itself may have burned out or seized, causing the control board to detect an open or abnormal circuit. A voltage reading at the pump terminals combined with no pump operation confirms internal motor failure.

  3. 03

    Interrupted door contact switch connection

    Wiring / connection

    An open or intermittent connection between the electronic control and the door contact switch can prevent the circulation pump circuit from completing. Check the switch wiring and connector integrity at both ends.

  4. 04

    Faulty door contact switch

    Part replacement

    The door contact switch itself may have failed internally, sending no signal to the SLT board and triggering the F78 fault. If wiring checks out, test the switch for continuity through its full range of motion.

  5. 05

    Defective SLT electronic control board

    Part replacement

    If voltage supply and wiring harness checks confirm power is present throughout but the pump still does not receive a proper output signal, the SLT control board may be at fault. This is typically the last component ruled out after other causes are eliminated.

See the test procedure for each cause

Frequently asked questions about F78

What does F78 mean on a Miele dishwasher?
F78 on a Miele dishwasher indicates a circulation pump fault. The control board has detected either a failed or non-functioning circulation pump, or an interrupted electrical connection between the control electronics and the door contact switch. The dishwasher will not complete a wash cycle until the fault is resolved.
Can I fix an F78 error myself, or do I need a technician?
Some causes of F78 can be addressed by a knowledgeable DIYer. Checking wiring harness connectors for looseness or corrosion and inspecting the door contact switch connections are reasonable first steps. However, measuring voltage at the SLT board terminals and replacing the circulation pump or control board typically requires electrical diagnostic experience and familiarity with dishwasher disassembly.
Is it safe to keep using my dishwasher when F78 is displayed?
No, you should not continue running the dishwasher while F78 is active. The circulation pump is not operating correctly, meaning water is not being properly circulated during the wash cycle. Running the appliance in this state can stress other components and will not produce clean dishes.
Will resetting my Miele dishwasher clear the F78 error?
A reset may temporarily clear the F78 code, but it will return if the underlying fault is not repaired. The error is triggered by a real electrical or mechanical condition, so resetting without fixing the wiring, door contact switch, or circulation pump will not resolve the problem.
How much does it cost to repair an F78 error on a Miele dishwasher?
Repair costs for an F78 fault vary depending on the root cause. A wiring repair or connector fix is typically on the lower end of the cost range. A circulation pump replacement on a Miele dishwasher generally falls in the range of $150 to $400 including parts and labor, while an SLT control board replacement can cost $200 to $500 or more depending on the specific model and service rates in your area.

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