High
E480 on Navien LCB700

Your boiler's hot water sensor has stopped sending a signal, which means it cannot tell how hot the water is and has stopped heating it to prevent overheating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

DHW Tank thermistor Open or Short Circuit

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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