Bosch Dishwasher Error Code F85

F85 on a Bosch dishwasher indicates a slide shutter signal change fault. The control board has detected a signal change at position switch B3/12, which monitors the slide shutter, even though the shutter was not actually activated. This is typically caused by dirty or intermittent switch contacts, loose wiring, or a failing switch rather than a mechanical failure of the shutter itself.

The F85 fault indicates a sensor or wiring issue rather than an immediate safety hazard like a water leak or electrical short. However, continued use with an active fault code is not recommended, as the slide shutter may not be functioning correctly and the dishwasher's wash or drying performance could be affected. Resolve the fault before running regular cycles to avoid potential secondary issues.

Performing a reset, such as cutting power to the dishwasher for a few minutes, may temporarily clear the F85 code. However, if the underlying problem with the position switch contacts, wiring, or control board has not been resolved, the fault will return. A reset alone is not a repair and should only be used to confirm whether the fault is persistent or intermittent while you work toward a proper diagnosis.

Some basic checks are within reach for a confident DIYer. Inspecting the wiring connectors near the slide shutter position switch for looseness or visible corrosion, and cleaning any contaminated contacts, can resolve the fault without professional help. However, testing for pulse signals at connector ST14 on the control board and accurately diagnosing a faulty switch or board typically requires a multimeter and some familiarity with appliance wiring. If you are not comfortable working around electrical components, a qualified technician should perform the diagnosis.

Repair costs vary depending on the root cause. If only cleaning the switch contacts or reseating a connector is needed, costs may be limited to a service call fee, typically in the range of $75 to $150. If the position switch B3/12 needs replacement, parts and labor combined generally fall in the $100 to $250 range. A control board replacement represents the most expensive scenario, with total costs often ranging from $200 to $450 or more depending on the specific model and local labor rates.