85 High

Navien 85 Fault Code

The Navien 85 fault code means: your boiler is having trouble 'talking' to its wireless thermostat, meaning it cannot receive signals to turn the heating or hot water on.. It appears on 1 Navien model in our database.

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: Radio communication: Communication to radio device interrupted
Typical repair cost £120-220 (including labour)

DIY fix possible

Check that your wireless thermostat controller has fresh batteries installedTurn the boiler off at the fused spur for 60 seconds and then turn it back on to reset the connectionEnsure there are no new large metal objects or electronic devices placed between the boiler and the thermostat that could block the signal

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Navien models that show the 85 fault code

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

Source

Navien 85 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 7 July 2026