BoilerFaultCodesYour heat pump has stopped making hot water because the sensor that monitors your cylinder's temperature is no longer communicating correctly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: DHW Cylinder Thermistor (T5) Error
What causes this fault?
This fault occurs when the main control board loses the electrical signal from the sensor inside your hot water tank. This usually happens because the sensor has failed internally due to age or because the wiring connecting the tank to the heat pump unit has become loose or damaged. Without this information, the system shuts down as a safety precaution because it cannot monitor how hot the water is getting.
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 E4 — 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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