E05
Bosch
Floor Temperature Sensor Fault
Thermostat displays E05 and indicates a floor sensor error (for hydronic or radiant floor applications).
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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 in‑slab Bosch NTC floor sensor, Open or shorted floor sensor cable, Incorrect sensor type or input configured, Loose terminal screws at thermostat sensor input
How to Fix / Troubleshooting
Safety: Turn off power to the heating system at the breaker before working on thermostat or sensor wiring.
- Check installer settings: In the advanced/installer menu, verify that the floor sensor is enabled only if installed, and that the correct Bosch NTC sensor type is selected.
- Inspect terminal connections: Remove the thermostat from the wall plate and tighten the floor sensor terminal screws. Ensure the conductors are fully inserted and not broken.
- Test sensor resistance: With power off, disconnect the floor sensor wires from the thermostat and measure resistance with a multimeter. Compare to Bosch’s temperature‑resistance chart. Infinite or near‑zero resistance indicates a failed sensor or cable.
- Check cable path: Where accessible (junction boxes, conduit), inspect for damage or splices that may have failed.
- Replace sensor: If the sensor is accessible (e.g., in conduit), pull in a new Bosch floor sensor. If embedded directly in concrete without conduit, consult a professional for alternative control strategies.
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Repair Difficulty
Hard
4/5
Required Part
Bosch Floor Temperature Sensor (NTC)
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