BoilerFaultCodesYour boiler is working fine, but your external thermostat or heating controls aren't 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 heating demand from low voltage controls (clamp 7-8-9)
What causes this fault?
This status code physically triggers when the internal circuit board is successfully waiting for a signal but the external thermostat has failed to send one. The most common reason is that the thermostat has lost power or the physical wiring connecting your wall controls to the boiler has developed a fault. Effectively, the boiler is 'listening' for the command to start, but the controls are staying silent.
This code is frequently seen during the first cold spell of autumn when homeowners turn their heating back on only to discover their thermostat batteries died over the summer.
DIY fix possible
Check that your room thermostat is turned up higher than the current room temperature.Replace the batteries in your wireless wall thermostat or programmer.Ensure your heating timer or smart app is set to an 'on' period.
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like S.36 — 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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