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F.64

Electronics / temperature sensor fault

The boiler has detected an electronics or NTC sensor/analogue-conversion fault.

What this code means

The boiler has detected an electronics or NTC sensor/analogue-conversion fault.

Possible causes

  • Flow or return NTC short circuit
  • Electronics or PCB fault

Common symptoms

  • F.64 displayed
  • Boiler may lock out or show abnormal temperature behaviour

Checks to make

  1. Arrange qualified diagnosis of NTC sensors, wiring and electronics

Safety

  • Do not remove the boiler casing or work on gas, combustion, flue or internal electrical components unless appropriately qualified. If gas is suspected, follow the national gas-emergency procedure.

Model notes

Vaillant notes that not every fault code is visible on every product model.