BoilerFaultCodesWhat the manual says
Manufacturer manualDEMAND ON
What causes this fault?
This is not actually a fault, but a status indicator showing that your thermostat or programmer has successfully requested heat. It confirms that the internal control board has received the electrical signal to start the ignition process for your heating or hot water. If the boiler is displaying this but not firing up, the issue likely lies with a secondary component rather than the initial request for heat.
DIY fix possible
Check your room thermostat is set to the desired temperatureEnsure your programmer or heating timer is switched to 'On'Wait for the boiler to complete its startup cycle as this light indicates normal operation
Avoid the next call-out bill
A cover plan would handle faults like NEON2: no call-out fees, no surprise bills.
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