BoilerFaultCodesYour boiler has lost communication with the internal temperature sensor for the heating system, meaning it cannot monitor how hot the water is getting.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: E-Combi EvoE-System EVOClas HE evo combiClas he evo system
What causes this fault?
This fault occurs when the boiler's main computer can no longer detect a signal from the sensor that monitors central heating water temperature. It is usually caused by a sensor that has reached the end of its life, or a loose wiring connection that has vibrated free over time. Without this data, the boiler shuts down as a safety precaution because it doesn't know if the water is getting dangerously hot.
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 705 — 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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