High
204 on Ariston Alteas One

Your boiler has lost its connection to the system's display screen or control board, meaning it cannot receive or process instructions properly.

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

Clas HE evoClas he evo systemE-combi evoE-system evo

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

202View →205View →

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