BoilerFaultCodesYour boiler is temporarily pausing to check its temperature sensors before starting up to ensure everything is working correctly.
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: 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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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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