TEC Low

Navien TEC Fault Code

The Navien TEC fault code means: your boiler has reached its internal timer for a routine service and is simply reminding you that it is time for a professional maintenance check.. It appears on 2 Navien models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Maintenance alarm. Generated when the power-on duration in days is greater than the value set at “W.Maintenance time”.
Typical repair cost £90-140 (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 TEC fault code

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

Source

Navien TEC 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 31 August 2026