BoilerFaultCodesNavien 302 Fault Code
The Navien 302 fault code means: your boiler has detected a significant temperature mismatch between its internal sensors, which means it has safely shut itself down to prevent potential overheating.. It appears on 5 Navien models in our database.
Technical description: 302:Eng head t'couple diff: Magnitude of the difference between the engine head control and limit thermocouples is greater than 100°C
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 302 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Navien 302 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 7 July 2026