High
E127 on Navien NCB 28 HE

Your boiler's air pressure sensor is failing to communicate properly, which means the safety system is preventing the burner from lighting to ensure the unit operates safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

APS error (open, short, initial value or no response)

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

E110View →

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