Navien · Water heater
E001 Heat exchanger overheating (water boiling)
What this code means
Water inside the heat exchanger is getting hot enough to boil, most often from a malfunctioning internal pump or trapped air in the recirculation loop.
Most likely causes
- Air trapped in the recirculation pump
- Failing internal circulation pump
- Restricted water flow through the heat exchanger
What to try first
Check the standby system pressure on the front panel; if a recirculation pump is installed, bleeding trapped air from it is the most common fix.
Safety note: if this code returns after one clean reset, stop resetting it — repeated lockouts usually mean a real fault that needs a licensed technician. Never bypass a safety switch.
FAQ
What does Navien error code E001 mean?
Heat exchanger overheating (water boiling). Water inside the heat exchanger is getting hot enough to boil, most often from a malfunctioning internal pump or trapped air in the recirculation loop.
Can I fix Navien code E001 myself?
Usually not. Check the standby system pressure on the front panel; if a recirculation pump is installed, bleeding trapped air from it is the most common fix. If the code returns after one reset, it needs a licensed technician.
What causes Navien code E001?
The most common causes are: air trapped in the recirculation pump; failing internal circulation pump; restricted water flow through the heat exchanger.
Other Navien water heater codes
All Navien water heater error codes →
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This information may contain errors or not apply to your exact model — always double-check it against your appliance's own manual before acting. If there's any chance of a gas, fire, electrical, carbon monoxide, or other safety hazard, stop and call a licensed professional or the appropriate agency (e.g. your gas utility) instead of relying on this page alone.