Low
66 on Sime Dewy 30/50 HE WM

Your boiler is receiving conflicting or faulty signals from an outdoor temperature sensor, which may cause your heating to run less efficiently or turn off unexpectedly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

External and ambient sensor influence

From this model's manual
Verified against the Sime Dewy 30 50 He Wm installation & service manual, page 17.
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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