031 Emergency

Navien 031 Fault Code

The Navien 031 fault code means: your boiler has detected an issue with the air supply or exhaust venting system, preventing it from operating safely.. It appears on 6 Navien models in our database.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description: Error 031
Typical repair cost £150-300 (including labour)

Engineer required

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

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Navien models that show the 031 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Navien 031 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