BoilerFaultCodesTechnical description
Return-Sensor check is running, demand (DHW or heating) is blocked
What causes this fault?
This occurs when the boiler's internal computer notices a mismatch between the temperature readings of its flow and return sensors. It stops the ignition process to ensure these sensors are reporting accurately and safely before firing up the burner. This is usually caused by a sensor that has become faulty or is struggling to detect temperature changes correctly as the system shifts from idle to active.
DIY fix possible
Wait 15 minutes for the automated self-test to finishCheck if the water pressure is between 1.0 and 1.5 barSwitch the boiler off and back on again to restart the check
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