BoilerFaultCodesTechnical description
The difference in heat between the safety sensor and the supply sensor is too large or the supply and return sensor have been interchanged.
What causes this fault?
This fault occurs when the boiler senses that the water inside the unit is heating up much faster than expected, which usually points to a lack of flow. This is most commonly caused by low system pressure, a blockage in the pipes, or a failing pump that isn't pushing the water around your radiators effectively. The boiler shuts down as a safety measure to prevent the heat exchanger from overheating.
This issue is frequently seen in autumn when heating systems are turned back on after being idle all summer, which can cause internal pump components to seize.
DIY fix possible
Check the pressure gauge on the front of the boilerIf the pressure is below 1 bar, use the filling loop to top it up to 1.5 barEnsure all radiator valves are fully open to allow water to flow freelyPress the reset button to clear the fault code