Medium
ALL 28 on Sime Murelle HE Regular

The boiler's control system is struggling to communicate with a specific accessory or secondary unit linked to your heating setup.

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

compatiBility input (s3) Error only for systEm 7

From this model's manual
Verified against the Sime Murelle He Regular installation & service manual, page 41.
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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