BoilerFaultCodesYour boiler has lost communication with the sensor that monitors your solar heating panels, likely due to a damaged or disconnected wire.
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 - Collector temperature sensor lead break
What causes this fault?
This fault occurs when the boiler's control system can no longer detect a signal from the temperature sensor located on your roof's solar panels. The most common reasons are a wire being damaged by wildlife, such as birds or squirrels, or a connection point becoming loose or corroded due to exposure to the elements.
This fault is often identified during the spring and summer months when homeowners notice their solar thermal system isn't contributing to their hot water production as expected.
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 9A — no call-out fees, no surprises.
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Viessmann Vitodens 333 is discontinued — time for a new one?
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