030
FAULT CODE
Navien
Abnormal Exhaust Temperature
High Severity
Engineer Required
The exhaust (flue gas) temperature is abnormal — either too high or there is a flue blockage. Manual reset required.
Cold Weather Note
Check flue terminal for ice blockage in cold weather.
Step-by-Step Fix Guide
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Step 1
Turn off the boiler
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Step 2
In cold weather, check the flue terminal for ice blockage
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Step 3 Engineer only
Call a Gas Safe engineer to inspect the flue system
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.