Navien · Water heater
E004 False flame detection
What this code means
The control board is detecting a flame signal when no flame should be present — a safety-critical fault distinct from E003's failure to ignite.
Most likely causes
- Sensor or flame rod issue giving a false reading
- Control board or wiring fault
- Improper grounding of the main electrical cord
What to try first
Verify the unit's power cord is properly grounded; beyond that this needs professional diagnosis given the safety implications.
Safety first: stop using the appliance and shut off its gas or power until it has been inspected — this fault category is associated with fire or gas risk.
FAQ
What does Navien error code E004 mean?
False flame detection. The control board is detecting a flame signal when no flame should be present — a safety-critical fault distinct from E003's failure to ignite.
Can I fix Navien code E004 myself?
No — stop using the appliance and shut off its gas or power until it has been inspected. This fault category is associated with fire or gas risk.
What causes Navien code E004?
The most common causes are: sensor or flame rod issue giving a false reading; control board or wiring fault; improper grounding of the main electrical cord.
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.