Boiler shows A16, heating temperature limited, boiler may cycle frequently

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.

Possible Causes

Faulty return NTC sensor on Fondital boiler, Poor sensor contact with pipe, Wiring damage to return sensor, Main PCB misreading sensor

Safety: Turn off power before any inspection.

User checks:

Reset: Reset the boiler once. If A16 persists, sensor diagnosis is required.

Technician actions:

Measure resistance of the return NTC sensor and compare with Fondital charts.
Ensure the sensor is properly clipped to the return pipe and has thermal paste if required.
Inspect the sensor cable for damage or loose connectors.
Test the main PCB sensor input.

Medium 3/5

Return NTC Sensor

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