What does error code E004 mean on a Navien tankless water heater?

False flame detection. The heater detected a flame when there shouldn't be one.

Can I fix Navien code E004 myself?

Start with these safe checks: Make sure the heater's power cord is plugged into a properly grounded outlet. If it continues, contact Navien technical support.

When should I call a technician for code E004?

If it continues, contact Navien technical support. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Navien tankless water heater error code

Navien tankless water heater code E004: False flame detection

Navien NPE-2 tankless water heaters

What E004 means

The heater detected a flame when there shouldn't be one.

Likely causes

Poor electrical grounding

Safe first checks

Make sure the heater's power cord is plugged into a properly grounded outlet.

When to stop

If it continues, contact Navien technical support.

Checked against: Navien NPE-2 user's information manual: understanding error codes. Codes can differ by model and year, so confirm with your owner's manual.