F.85 error, boiler may not start, both NTC sensors reported faulty

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

Both NTCs disconnected, Harness unplugged from PCB, Common wiring break, Incorrect wiring after service

Safety: Isolate power.

Steps:

Check that both flow and return NTCs are connected to the correct PCB terminals.
Inspect the shared harness for breaks or unplugged connectors.
Reconnect any loose plugs and secure them.

If wiring is intact and sensors test correctly, a PCB fault is likely and requires professional replacement.

Medium 3/5

NTC Sensor Wiring Harness

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