BoilerFaultCodesYour boiler has detected an incorrect setting or a communication error regarding the minimum water temperature required when an external control system asks for heat.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Minimum set boiler water temperature in case of external demand
What causes this fault?
This fault occurs when there is a mismatch between the boiler's internal computer and the external smart controls or thermostat. It usually happens because the minimum heat level requested by the external system is set higher than what the boiler is programmed to allow, causing a configuration conflict.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 9b:70 — no call-out fees, no surprises.
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