Navien · Water heater
E016 Heat exchanger overheating
What this code means
The heat exchanger temperature has exceeded its safe operating range — one of the most commonly reported Navien codes across support documentation.
Most likely causes
- Clogged cold water inlet filter restricting flow
- Partially closed main water supply valve
- Scale buildup in the heat exchanger needing a flush
What to try first
Turn the unit off for 30 minutes, then clean the cold water inlet filter and strainer before restarting.
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 E016 mean?
Heat exchanger overheating. The heat exchanger temperature has exceeded its safe operating range — one of the most commonly reported Navien codes across support documentation.
Can I fix Navien code E016 myself?
Usually not. Turn the unit off for 30 minutes, then clean the cold water inlet filter and strainer before restarting. If the code returns after one reset, it needs a licensed technician.
What causes Navien code E016?
The most common causes are: clogged cold water inlet filter restricting flow; partially closed main water supply valve; scale buildup in the heat exchanger needing a flush.
Other Navien water heater codes
All Navien water heater error codes →
Other water heater brands: Rheem · Ruud · Rinnai · Noritz · Takagi · A.O. Smith · Bradford White · State / American · Generic electric · Generic tankless
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.