High
E762 on Navien NCB 35 HE

Your boiler is struggling to detect the exhaust vent, likely because the flue pipe is not fitted securely or is the wrong size for your home.

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

Vent installation detector error; can appear if the vent pipe is not correctly sized or has not been inserted properly.

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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