High
E321 on Baxi Suprima 50

Your boiler has lost its ability to measure the temperature of your hot water properly, which means it cannot safely heat your water to the right level.

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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Related fault codes

E125View →E110View →

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