High
H.01.18 on Baxi Assure System

Your boiler has detected that water is not moving through your heating system properly and has temporarily stopped itself to prevent overheating.

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

No water circulation (temporary). INSUFFICIENT CIRCULATION Check the installation pressure Activate a manual venting cycle Check the operation of the pump Check the boiler/installation circulation TEMPERATURE SENSOR ERROR Check the operation of the temperature sensors Check the temperature sensor connection

From this model's manual
Verified against the Baxi Bm Baxi B Basic System 2 600 800 Assure 500 Isim installation & service manual, page 49.
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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