BoilerFaultCodesYour boiler's computer is confused because it thinks internal temperature sensors are plugged into the wrong place, preventing the unit from operating safely.
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 incorrectly connected: A temperature sensor is connected to the IUM.
What causes this fault?
This fault occurs when the boiler's control board detects that the internal temperature sensors are plugged into the wrong terminals or have been cross-wired. It is almost always caused by a component failure within the internal computer module or a wiring harness that has worked loose or degraded over time.
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 Fault 33 / 22 — 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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