High
E321 on Baxi Suprima 115

Your boiler has detected a problem with the sensor that monitors hot water temperature, meaning it cannot safely heat water for your taps.

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

Hot water negative temperature coefficient (NTC) fault.

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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