BoilerFaultCodesTechnical description
Return sensor fault
What causes this fault?
This fault occurs when the boiler's control board loses communication with the sensor that monitors water returning from your heating system. The most common reason is that the internal sensor has developed a chemical failure or electrical short, preventing the boiler from knowing if it is safe to continue firing. In some cases, it can also be caused by loose or damaged wiring connecting that sensor to the main computer.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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