How much does it cost to fix Navien error code E205?

Typical repair cost for the Navien E205 fault is £120-220 including labour.

E205 High

Navien E205 Fault Code

Q: What does the Navien E205 fault code mean?

Your boiler has lost the ability to accurately measure the temperature of the water being sent to your radiators, so it has safely shut itself down to prevent overheating.

The Navien E205 fault code means: your boiler has lost the ability to accurately measure the temperature of the water being sent to your radiators, so it has safely shut itself down to prevent overheating.. It appears on 7 Navien models in our database.

Technical description: Heating supply thermistor open or short circuit

Typical repair cost £120-220 (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 E205 fault code

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

Source

Navien E205 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