218 High

Navien 218 Fault Code

The Navien 218 fault code means: your boiler has detected an issue with the water flow or pressure sensor, meaning it cannot accurately tell if water is moving through the system to heat it safely.. It appears on 6 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: Error 218
Typical repair cost £150-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Navien models that show the 218 fault code

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

Source

Navien 218 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