BoilerFaultCodesYour boiler has detected that the internal temperature sensors have been mixed up or are reading in the wrong order, preventing it from heating your water safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow and return sensors swapped
What causes this fault?
This fault occurs when the boiler's control board detects that the temperature readings for the outgoing and incoming water pipes are reversed. It usually happens because the physical sensors have been clipped onto the wrong pipes during a repair, or the internal wiring harness has been connected incorrectly. In some cases, a faulty sensor sending an illogical reading can trick the computer into thinking the parts are swapped.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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