BoilerFaultCodesTechnical description
Flue thermistor error
What causes this fault?
This fault occurs when the boiler's control system receives an incorrect or missing signal from the sensor located in the exhaust flue. The most common reason is that the sensor itself has failed due to age or heat exposure, though it can also be triggered by a loose electrical connection or moisture affecting the internal wiring.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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