BoilerFaultCodesYour boiler is having trouble talking to the solar heating system, which may prevent your home from using energy from your solar panels efficiently.
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: Control mode - Communication fault-solar control unit
What causes this fault?
This fault occurs when the main boiler computer loses its digital connection with the solar thermal control system. The most common reason is a loose or damaged communication cable between the two units, or a component failure within the solar control module itself.
This issue is often first noticed in spring or summer when homeowners expect their solar panels to begin providing the majority of their hot water.
DIY fix possible
Check that the solar control unit is switched on and has powerTurn the boiler power off at the fused spur, wait 30 seconds, and turn it back on to reset the connectionInspect any visible cables between the boiler and the solar controller for obvious signs of damage or loose plugs
Find a Gas Safe engineer
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A boiler cover plan would cover faults like C2 — no call-out fees, no surprises.
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