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Error code reference

Miele Dishwasher Error Code F87

Sensor softener fault

Miele codesMiele dishwasher codes

Sensor softener fault — break in data transfer between sensor softener and electronic module; emergency program operates.

First step from the service manual

Check for approx. 9 VAC to sensor softener 10N1 electronic module; check data connection for open circuit.

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

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What F87 means on a Miele dishwasher

Error code F87 on a Miele dishwasher indicates a fault in the sensor softener system, specifically a break in data transfer between the sensor softener unit (component 10N1) and the main electronic control module. The sensor softener is responsible for monitoring and managing the water softening process, which conditions incoming water to prevent limescale buildup on internal components and the dishwasher's heating element. When communication between this sensor and the control board is interrupted, the appliance cannot regulate softening performance and will revert to an emergency operating program to allow limited continued use.

The diagnostic process begins with verifying that approximately 9 VAC is present at the sensor softener 10N1 and the electronic module. If that supply voltage is confirmed, the fault points toward the data connection itself rather than the power supply. An open circuit in the data line, caused by a broken wire, corroded connector pin, or a damaged connector housing, will prevent the digital signal from passing between the two components. Intermittent faults of this type can be caused by vibration over time loosening connector fittings.

In some cases, the sensor softener unit itself has failed internally, making it unable to transmit valid data even when voltage and wiring are intact. The emergency program that activates during an F87 fault allows the dishwasher to continue operating but without proper softening control, meaning the unit should not be run extensively in this state, particularly in hard water areas, as limescale damage to the heating element and spray arms can accumulate.

Source: manufacturer service documentation.

Common causes of F87

  1. 01

    Open circuit in the data connection wiring

    Part replacement

    A broken or severed wire in the data line between sensor softener 10N1 and the electronic module will completely stop communication. Inspect the wiring harness along its full length for visible breaks, pinched sections, or chafing against cabinet edges.

  2. 02

    Corroded or disconnected connector

    Wiring / connection

    Moisture inside the dishwasher cabinet can cause connector pins to corrode, or vibration over time can cause a connector to loosen from its socket. Check all connectors between the sensor softener and the control module for secure seating and clean pin contact surfaces.

  3. 03

    Insufficient supply voltage to sensor softener

    Wiring / connection

    If the sensor softener is not receiving approximately 9 VAC from the electronic module, it cannot operate or transmit data. Use a multimeter set to AC voltage to confirm proper supply voltage at the 10N1 component terminals.

  4. 04

    Failed sensor softener unit (10N1)

    Part replacement

    If voltage and wiring are confirmed good, the sensor softener unit itself may have failed internally and is no longer capable of sending valid data signals. Component replacement is required in this scenario.

  5. 05

    Faulty electronic control module

    Part replacement

    In rare cases the main electronic module may have lost the ability to send power to or receive data from the sensor softener circuit. This is typically only suspected after all wiring and the sensor unit have been ruled out as the cause.

See the test procedure for each cause

Frequently asked questions about F87

What does F87 mean on a Miele dishwasher?
F87 indicates a break in data transfer between the sensor softener unit and the main electronic control module. The dishwasher detects that communication with the softener sensor has been lost and activates an emergency operating program. The fault can stem from a wiring break, a faulty connector, insufficient supply voltage to the sensor, or a failed sensor softener component.
Can I fix F87 on my Miele dishwasher myself?
Some steps are accessible to a confident DIYer, such as inspecting connectors for loose or corroded pins and checking for visible wire damage. However, verifying the 9 VAC supply voltage at the sensor softener requires a multimeter and basic electrical knowledge. Replacing the sensor softener unit or the control module is best handled by a qualified technician familiar with Miele appliances.
Is it safe to keep using my Miele dishwasher when F87 is showing?
The dishwasher switches to an emergency program during an F87 fault, which allows limited continued use. However, running the appliance extensively in this state is not recommended, especially in hard water areas, because the water softening system is not functioning and limescale can build up on the heating element and internal parts over time.
Will resetting the dishwasher clear the F87 error code?
A reset may temporarily clear the displayed fault code, but if the underlying wiring fault, connector problem, or failed component has not been repaired, the F87 error will return once the appliance attempts to communicate with the sensor softener again. The root cause must be diagnosed and corrected for the fault to stay resolved.
How much does it cost to repair a Miele dishwasher F87 fault?
Repair costs vary depending on what is causing the fault. If only a connector needs reseating or a wire needs repair, costs may be limited to a service call fee, typically in the range of $80 to $150. If the sensor softener unit requires replacement, parts and labor combined can range from $150 to $400 or more. Control module replacement is the most expensive scenario and can push costs higher.

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