High
7 05 on Ariston Clas HE 35

Your boiler is struggling to detect water flow between its internal heating circuits, which means it will likely stop providing heating and hot water until the faulty sensor is replaced.

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.

What the manual says

Manufacturer manual

Hydraulic separation sensor defective

From this model's manual
Verified against the Ariston Clas He 24 installation & service manual, page 38.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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

7 01View →7 02View →7 03View →

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