How much does it cost to fix Navien error code E46?

Typical repair cost for the Navien E46 fault is £120-200 including labour.

E46 Low

Navien E46 Fault Code

Q: What does the Navien E46 fault code mean?

Your boiler is struggling to detect the outside temperature, so it is defaulting to a basic heat setting to keep your home warm while ignoring external weather conditions.

The Navien E46 fault code means: your boiler is struggling to detect the outside temperature, so it is defaulting to a basic heat setting to keep your home warm while ignoring external weather conditions.. It appears on 6 Navien models in our database.

Technical description: Outdoor sensor error

Typical repair cost £120-200 (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 E46 fault code

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

NCB Repair: £120-200
NCB 28 HE Repair: £120-200
NCB 35 HE Repair: £120-200
NCB 40 HE Repair: £120-200
NCB H Repair: £120-200
NHB 29 Repair: £120-200

Source

Navien E46 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