Low
E740 on Navien NCB H

Your boiler is struggling to read the temperature outside, which means it cannot automatically adjust your heating to match the weather conditions.

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.

Technical description

Abnormal operation: outdoor temperature sensor (appears only when the outdoor reset curve is enabled).

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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