BoilerFaultCodesTechnical description
Flow / Return - sensor check is running, demand (DHW or heating) is blocked
What causes this fault?
This code appears when the boiler’s control board notices a discrepancy between the temperature readings of the flow and return sensors. It pauses the ignition process to test if these sensors are accurately tracking the heat of the water before allowing the burner to fire up. The most common reason is that one sensor has become faulty or is providing a sluggish reading compared to the other.
DIY fix possible
Wait for up to 15 minutes as this is often a self-correcting safety checkEnsure your radiator valves are open to allow water to flowCheck that the boiler pressure is between 1.0 and 1.5 bar on the gauge
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