BoilerFaultCodesNavien E05 Fault Code
The Navien E05 fault code means: your boiler has detected an issue with the internal ventilation system that prevents it from safely clearing exhaust gases, so it has stopped working to keep your home safe.. It appears on 6 Navien models in our database.
Technical description: Fan error
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Navien models that show the E05 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Navien E05 fault code information on this page is sourced and cross-checked against the official Navien service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026