A10
Fondital Flow/Return NTC Sensor Fault

Boiler displays A10; the heating temperature reading is incorrect or fluctuates rapidly.

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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 short-circuited flow NTC sensor, Damaged sensor cable on Fondital boiler, Poor contact at the NTC connector on the PCB, Water ingress into the sensor pocket

How to Fix / Troubleshooting

Safety: Turn off power before any inspection. Do not remove covers that require tools.

User checks:

  • Reset: Reset the boiler once. If A10 reappears, a sensor or wiring fault is likely.
  • Visual check: Look for obvious damage to external sensor cables (if visible) without removing panels.

Technician actions:

  • Measure the resistance of the flow and return NTC sensors at various temperatures.
  • Inspect and replace any damaged NTC wiring harness or connectors.
  • Check for leaks around the sensor pockets and repair if necessary.
  • Verify the main PCB sensor input circuits.
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Repair Difficulty

Medium 3/5

Required Part

Flow NTC Sensor
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