BoilerFaultCodesYour boiler is not currently experiencing a fault; it is simply performing a routine data check or start-up sequence.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Control panel sequence reads the unit data
What causes this fault?
The 'd' code appears when the boiler's internal computer is reading and verifying the system data during its initial start-up or after a power cycle. It is a normal part of the boiler's internal checks rather than a mechanical failure. Your boiler has not stopped due to a problem, but is simply finishing its 'handshake' process before it begins heating your home.
DIY fix possible
Wait for a few minutes for the sequence to finishMonitor the display to see if it changes to a standard operating codeIf the screen stays stuck on 'd' for over an hour, try a simple reset
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