Medium
ALL 04 on Sime Murelle Advanced HE MkII Combi

Your boiler is struggling to detect the temperature of the hot water it produces, which will likely stop your taps and shower from getting warm.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Domestic hot water sensor (SS) fault

From this model's manual
Verified against the Sime Murelle Advanced He Combi installation & service manual, page 32.
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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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