BoilerFaultCodesYour boiler's internal temperature sensors have likely been plugged into the wrong sockets or have developed a wiring fault, meaning the system cannot accurately track how hot the water is.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Temperature sensors (T1 and T2) reversed.
What causes this fault?
This fault occurs when the boiler's control board detects that the temperature readings from the flow and return pipes are swapped or illogical. The most common reason is that the internal sensors were plugged into the wrong ports during a recent repair, or a fault in the wiring harness is sending confusing signals to the main computer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 52124 — no call-out fees, no surprises.
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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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