How much does it cost to fix Navien error code E596?

Typical repair cost for the Navien E596 fault is £90-180 including labour.

E596 Medium

Navien E596 Fault Code

Q: What does the Navien E596 fault code mean?

Your boiler has lost its digital connection to your room thermostat, meaning it cannot receive signals to turn the heating on or off.

The Navien E596 fault code means: your boiler has lost its digital connection to your room thermostat, meaning it cannot receive signals to turn the heating on or off.. It appears on 6 Navien models in our database.

Technical description: Communication Error with Smart Room Controller

Typical repair cost £90-180 (including labour)

DIY fix possible

Switch off the power to the boiler at the fused spur or consumer unit.Wait 5 minutes to let the system fully reset.Turn the power back on and check if the thermostat re-establishes its connection with the boiler.

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Navien models that show the E596 fault code

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

Source

Navien E596 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