BoilerFaultCodesTechnical description
Flow return sensor check is running demand is block
What causes this fault?
This status occurs when the boiler's internal computer notices that the temperatures on the flow and return pipes are not changing in the way it expects. To prevent damage, the boiler pauses operation to double-check that the sensors are reporting accurately and that water is actually moving through the heat exchanger. This is often caused by a failing pump or a buildup of debris that is slowing down the flow of water.
This issue is more common during the first cold snap of autumn when a pump that has been idle all summer fails to restart correctly.
DIY fix possible
Check that all radiator valves are fully openEnsure your central heating system pressure is between 1.0 and 1.5 barWait up to 15 minutes for the boiler to complete its automatic recalibration