High
6 04 on Ariston Clas HE Evo

Your boiler has stopped working because the mechanical fan that pushes stale air out of the flue is not spinning fast enough to run safely.

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

Insuffi cient fan speed

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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