High
1 09 on Ariston Clas Net One

Your boiler has detected that the water pressure inside your heating system is too high, which can cause internal leaks or force the safety valve to open.

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

System pressure > 3 bar

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

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