BoilerFaultCodesYour boiler is temporarily paused because it is running a self-diagnostic check on its internal temperature sensors to ensure they are 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: Automatictestprogramme:Returntemperaturesensor,heatingdemandsblocked.
What causes this fault?
This code appears when the boiler's internal computer notices a potential discrepancy between the flow and return temperature readings. It triggers a brief pause to double-check that the sensors are reporting accurately before allowing the burner to fire up again. Usually, this is caused by a sensor that is starting to drift out of its correct calibration or a minor circulation issue.
DIY fix possible
Wait up to 15 minutes for the automatic test to completeEnsure all radiator valves are open to allow water flowReset the boiler if the code persists for more than 20 minutes
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