BoilerFaultCodesTechnical description
Open circuit on coding resistor
What causes this fault?
This fault occurs when the boiler's main control board loses contact with a small internal component that tells the computer which specific model it is installed in. The most common reason is a loose electrical connection or a failed resistor chip, which prevents the boiler from operating safely because it no longer knows its own power settings.
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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