Navien · Water heater
E012 Flame loss during operation
What this code means
The unit lit successfully but the flame dropped out mid-cycle, distinct from E003's failure to ignite in the first place.
Most likely causes
- Low or unstable gas pressure
- Undersized gas line or bad regulator
- Internal gas valve fault
- Scale or carbon buildup on internal components
What to try first
Descaling and gas pressure checks are the usual fixes but involve isolation valves and combustion parts — professional service is strongly recommended.
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 E012 mean?
Flame loss during operation. The unit lit successfully but the flame dropped out mid-cycle, distinct from E003's failure to ignite in the first place.
Can I fix Navien code E012 myself?
Usually not. Descaling and gas pressure checks are the usual fixes but involve isolation valves and combustion parts — professional service is strongly recommended. If the code returns after one reset, it needs a licensed technician.
What causes Navien code E012?
The most common causes are: low or unstable gas pressure; undersized gas line or bad regulator; internal gas valve fault; scale or carbon buildup on internal components.
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.