High
711 on Ariston Alteas One

Your boiler has lost track of the temperature of the water coming back from your radiators, which may stop your heating from working efficiently or starting up at all.

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

Return sensor defective (zone 1)

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

701View →712View →713View →

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