Miele Dishwasher Error Code F26 — Boiler/Thermoblock NTC Fault
What this means
Error F26 on Miele dishwashers with a separate boiler or thermoblock for hot rinse water indicates the NTC sensor in that module is faulty. Miele premium dishwashers often have a dedicated boiler that heats rinse water to a higher temperature for superior drying and sanitizing. If its temperature sensor fails, the machine cannot safely operate the boiler and will display F26.
Alternate codes: F 26
Step-by-step fix
4 stepsIdentify if your model has a thermoblock
Check your Miele dishwasher model number in the owner's manual or on the rating plate (inside the door frame). Models with a thermoblock (e.g., G 7000 series) use a separate instantaneous water heater for the final rinse.
If your model does not have a thermoblock, F26 may instead relate to a secondary heating sensor — consult Miele documentation for your specific model.
Access and test the thermoblock NTC
Unplug the dishwasher and remove the base plate. Locate the thermoblock module — it is a compact unit with water connections and electrical connections. Find the NTC sensor (small cylindrical probe). Disconnect and test with a multimeter for the expected resistance.
The thermoblock NTC may have a different resistance value than the main tub NTC — check Miele's service manual for your model.
Inspect wiring to the thermoblock
Check all wiring between the thermoblock and the control board. Vibration during shipping or over years of use can loosen connectors.
The thermoblock area can get very hot during operation — look for heat-damaged wires or melted connectors.
Replace the thermoblock NTC sensor
If the sensor tests faulty, replace it. On some Miele models the sensor is a separate part; on others it is integrated into the thermoblock and the entire unit must be replaced.
If the entire thermoblock needs replacement, this is typically a professional-level repair due to the water and electrical connections involved.
When to call a professional
Thermoblock replacement is complex and involves both plumbing and electrical connections. A Miele-certified technician is recommended for this repair.
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.
Learn more about our sourcesParts you may need
Thermoblock Unit
Part #10306060 · $200–$400
If sensor is integrated and thermoblock is damaged
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