107
Ariston External Sensor Detection Failure

Thermostat displays error 107 and cannot detect any external room sensor or floor sensor connected.

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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

External sensor not connected to correct terminals, Broken external sensor cable, Wrong sensor type (resistance value) for Ariston thermostat, Faulty external NTC sensor

How to Fix / Troubleshooting

Safety: Isolate power to the thermostat before wiring changes.

  • Check wiring terminals: Open the thermostat backplate and verify the external sensor wires are connected to the designated sensor terminals (often marked S1/S2 or NTC). Do not connect them to bus or relay terminals.
  • Test sensor resistance: With a multimeter, measure resistance across the sensor leads at room temperature. Compare with the value specified in the Ariston manual (e.g. ~10 kΩ at 25°C). If open circuit or far off spec, replace the sensor.
  • Check cable continuity: If the sensor is remote (e.g. floor probe), test continuity of the cable from thermostat to sensor. Repair or replace damaged cable.
  • Configure sensor mode: In the installer menu, enable external sensor use (room/floor) and disable it if not installed to clear the error.
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Repair Difficulty

Medium 3/5

Required Part

Ariston External NTC Room/Floor Sensor
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