Floor Sensor Err
Worcester Bosch
External floor temperature sensor open or short circuit
Thermostat configured for underfloor heating shows 'Floor Sensor Err' or similar; floor temperature not displayed.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Damaged floor sensor cable, Loose terminal connection at thermostat, Incorrect sensor type configured, Sensor crushed or cut during floor works
How to Fix / Troubleshooting
Safety first: Isolate power to any underfloor heating manifold controls before opening wiring centres. Thermostat terminals are usually low‑voltage but may be near mains wiring.
- Check wiring at thermostat: Remove the thermostat from the wall and inspect the floor sensor terminals. Ensure both sensor wires are firmly clamped and not broken.
- Verify configuration: In the installer menu, confirm that the thermostat is set to use an external floor sensor and that the correct sensor type (e.g. 10k NTC) is selected if configurable.
- Continuity test (advanced): With power off, disconnect the sensor wires and use a multimeter to measure resistance across the sensor. A typical NTC sensor will show several kΩ at room temperature. Infinite (open) or near‑zero (short) resistance indicates a failed sensor or cable.
- If cable is damaged in floor: The floor sensor usually cannot be repaired without major work. Many systems allow switching to air‑sensor control only; otherwise, a new sensor may be run in a spare conduit if available.
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Repair Difficulty
Hard
4/5
Required Part
Underfloor Heating Floor Temperature Sensor (NTC)
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