BoilerFaultCodesYour boiler is not receiving the electrical signal from your thermostat or programmer 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: Failure in the electrical supply to the boiler; check fuses and 230V mains input.
What causes this fault?
This fault occurs when the boiler is receiving main power but isn't getting the specific 230V command to actually start heating. The most common reason is a failure in an external component like a broken room thermostat, a blown fuse in the wiring center, or a motorized valve that is stuck and failing to trigger the microswitch. Essentially, the boiler is 'waiting' for a signal that never arrives because of a break in the electrical chain outside the unit itself.
This issue is frequently seen during the first cold snap of autumn when heating systems are turned on for the first time after being idle all summer, often revealing a seized zone valve or a thermostat with dead batteries.
DIY fix possible
Ensure your wall thermostat is turned up higher than the current room temperatureCheck that your programmer or heating timer is set to 'ON' or 'AUTO'Check your home's consumer unit (fuse box) to see if any switches have trippedReplace the batteries in your room thermostat if it has a digital display
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A boiler cover plan would cover faults like No Switched Live — no call-out fees, no surprises.
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Potterton Promax 15 & 24 is discontinued — time for a new one?
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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