BoilerFaultCodesYour boiler is not receiving the signal to turn on the heating, which is likely caused by an issue with your external thermostat or the internal timer.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Is not illuminated: Ensure all controls (selector switch, programmer, and room stat) are calling for heat. Check programmer for 3 Vdc at PCB connector A9.
What causes this fault?
This fault occurs when the boiler is waiting for a command to start but isn't receiving the necessary electrical signal from your heating controls. The most common reason is that your wall thermostat or plug-in timer has failed, or is simply not set to a high enough temperature to trigger the boiler. Essentially, the boiler is healthy but the 'remote control' telling it to turn on is broken or disconnected.
This issue is frequently discovered during the first cold snap of autumn when homeowners first try to switch their heating back on after the summer months.
DIY fix possible
Check that your room thermostat is turned up higher than the current room temperature.Ensure the boiler's main selector switch is set to 'Heating and Hot Water'.Check your programmer or timer to ensure the heating is set to 'ON' or 'Auto'.Replace the batteries in your wireless room thermostat if it has them.
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