E353 High

Navien E353 Fault Code

The Navien E353 fault code means: your boiler has detected an issue with how it manages water flow and pressure, which means it cannot safely produce hot water for your taps or home.. It appears on 7 Navien models 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: DHW Heat Exchanger: Water leaks; Low temperature water in the heat exchanger; Water pressure sensor: Unable to detect or measure changes of water pressure
Typical repair cost £180-350 (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 E353 fault code

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

Source

Navien E353 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