BoilerFaultCodesYour boiler has detected an internal electronic error or a communication failure that is preventing it from heating your home.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Reset the boiler. If the fault reoccurs, contact a heating engineer.
What causes this fault?
These codes are triggered by a breakdown in communication between the boiler's internal electronic components or a failure within the main control board itself. It often occurs when the circuit board can no longer process data correctly or when the electrical signals sent between parts become unstable. Essentially, the boiler's 'brain' has encountered an error it cannot recover from automatically, leading to a complete shutdown.
DIY fix possible
Locate the mode selector switch on the front panelTurn the switch to the 'OFF/RESET' positionWait 30 seconds, then turn the switch back to either 'Heating' or 'Hot Water' mode
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A boiler cover plan would cover faults like AL79 — 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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