BoilerFaultCodesYour boiler has lost communication with one of its internal control modules or an external smart accessory, causing it to use temporary backup settings.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Monitoring LON users: When there is no response from a user, values defaulted inside the control unit continue to be used for a further 20 minutes. Only then will a fault message be triggered.
What causes this fault?
This fault occurs when the boiler's main brain loses its connection to a secondary component or smart control accessory. The most common reason is a communication breakdown caused by loose wiring, a faulty connection module, or a malfunction in the main circuit board. While the boiler tries to cope using backup settings for a short period, it eventually triggers this code when it can no longer get the data it needs to operate efficiently.
DIY fix possible
Turn the boiler power off at the main fused spur switch.Wait for 30 seconds.Turn the power back on and see if the communication link re-establishes itself.
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