F.72 error, boiler may overheat or show inconsistent temperatures

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

One NTC sensor out of calibration, Poor contact between sensor and pipe, Air in system causing false readings, PCB sensor input fault

Safety: Turn off power and allow the system to cool.

Checks:

Ensure both NTC sensors are firmly attached to the pipes with good thermal contact and insulation.
Bleed air from the system and verify correct pressure.
Measure both NTC resistances at similar temperatures; large discrepancies indicate a faulty sensor.
Replace the faulty NTC sensor with a Vaillant-approved part.

If both sensors test correctly, a PCB fault is possible and should be assessed by a professional.

Medium 3/5

Return NTC Temperature Sensor

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