Technical description
Maintenance (only with weather-compensated control unit)
What causes this fault?
This code is triggered by the boiler’s internal timer, which tracks how many months or operating hours have passed since the last professional inspection. It is an automated reminder set by a heating engineer to ensure the system remains efficient and safe. There is no physical breakage or component failure causing this display; it is simply a proactive prompt for routine maintenance.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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