BoilerFaultCodesTechnical 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 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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