Medium
65 on Sime Dewy 30/130 HE FS

Your boiler is receiving a signal from an external device, such as a smart thermostat or weather sensor, that is preventing it from firing up as normal.

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

Operating mode of external contact

From this model's manual
Verified against the Sime Dewy 30 130 He Fs installation & service manual, page 18.
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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