A12
Fondital DHW NTC Sensor Fault

Error A12, unit may lock out immediately on start-up.

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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

Open or shorted DHW NTC, Sensor dislodged from pipe or heat exchanger, Wiring damage, Control board input failure

How to Fix / Troubleshooting

Safety: Turn off power and water supply if removing any wet components.

  • Locate DHW NTC: On Fondital combi water heaters, the DHW sensor is usually clipped to the DHW outlet pipe or integrated into the plate heat exchanger manifold.
  • Check seating: Ensure the sensor is firmly in contact with the pipe or in its pocket, with thermal paste if specified.
  • Inspect wiring: Look for broken insulation or pulled wires. Reseat the connector on the control board.
  • Replace sensor: If the sensor is physically damaged or readings are clearly wrong, install a new DHW NTC sensor.
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Repair Difficulty

Medium 3/5

Required Part

DHW NTC Temperature Sensor
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