BoilerFaultCodesA sensor that monitors water temperature for your main heating area has stopped working correctly, which may prevent your radiators from heating up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Send sensor defective (Zone 1)
What causes this fault?
This fault occurs when the internal sensor responsible for monitoring the temperature of the water leaving the boiler for your central heating stops sending a reliable signal. The most common reason is that the sensor has developed an electrical fault or has been damaged by wear and tear, meaning the boiler can no longer safely regulate your heating. In some cases, loose or damaged wiring between this sensor and the main control board can also trigger the error.
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 701 — 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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