BoilerFaultCodesYour boiler is not receiving the electrical signal from your thermostat or timer telling it to turn on.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No 230V at sL to N; check external controls and mains supply.
What causes this fault?
This fault occurs when the boiler is powered on but isn't receiving the necessary electrical 'command' from your external controls to start heating. The most common reason is a failure in the communication line between your room thermostat, programmer, or motorized valves and the boiler itself. Essentially, the boiler is waiting for a green light to fire up that never arrives because of a fault in those external components.
This issue is frequently discovered during the first cold snap of autumn when homeowners switch their heating back on after months of inactivity, causing stuck motorized valves to fail.
DIY fix possible
Check that your room thermostat is turned up higher than the current room temperature.Ensure your programmer or heating timer is set to 'ON' or 'AUTO'.Replace the batteries in your wireless thermostat if the screen is blank or showing a low battery symbol.
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A boiler cover plan would cover faults like SWITCHED LIVE — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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