Medium
i4 on Sime Metropolis DGT 25 BF

Your boiler has detected a communication error with an external temperature sensor, which may prevent it from operating correctly or heating your home.

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

Auxiliary sensor AUX temperature

From this model's manual
Verified against the Sime Metropolis Dgt 25 Bf installation & service manual, page 19.
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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