Technical description
operating mode codes
What causes this fault?
These codes appear because the boiler is communicating its current stage of operation, such as starting the fan or heating the water to the required temperature. They are triggered by normal requests for heating or hot water and do not indicate that anything has broken. Think of them as the boiler providing a live progress report on its internal sequence.
DIY fix possible
Check that your thermostat is set to the desired temperatureEnsure the gas and water supply valves are openMonitor the display to see if the code changes as the boiler completes its cycle
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