How much does it cost to fix Navien error code E593?

Typical repair cost for the Navien E593 fault is £150-300 including labour.

E593 High

Navien E593 Fault Code

Q: What does the Navien E593 fault code mean?

Your boiler's electronic control panel is experiencing a communication fault, which prevents the display from responding or controlling the unit properly.

The Navien E593 fault code means: your boiler's electronic control panel is experiencing a communication fault, which prevents the display from responding or controlling the unit properly.. It appears on 6 Navien models in our database.

Technical description: Abnormal operation: Touch IC (Panel PCB)

Typical repair cost £150-300 (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 E593 fault code

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

NCB Repair: £150-300
NCB 28 HE Repair: £150-300
NCB 35 HE Repair: £150-300
NCB 40 HE Repair: £150-300
NCB H Repair: £150-300
NHB 29 Repair: £150-300

Source

Navien E593 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