High
d9 on Remeha Avanta

Your boiler has detected that the water inside is heating up too quickly or is struggling to circulate, so it has safely shut itself down to prevent internal damage.

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

Shut down; maximum temperature rise is exceeded or the dT between the supply and return temperature ≥ 45°C or a rate of rise in the flow temperature > 1°C/sec

From this model's manual
Verified against the Remeha Avanta installation & service manual.
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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