BoilerFaultCodesYour boiler has lost communication with its external controls, such as your thermostat, often due to an electrical wiring error or interference.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: eBUS undervoltage | Short circuit on eBUS, overload on eBUS or two power sources on eBUS with different polarity
What causes this fault?
This fault occurs when there is an electrical conflict or a lack of power on the digital communication line that connects your boiler to your thermostat. It is usually caused by wires being accidentally crossed during installation, a physical short circuit in the cabling, or an internal electronic failure in the control module. Effectively, the boiler can no longer 'hear' what the thermostat is telling it to do, so it shuts down for safety.
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 F.49 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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