Navien Error Code E001: Ignition Failure

Severity: Warning
Type: digital display
Where to look: front panel

Warning: Your Navien boiler or water heater is locked out because the burner failed to light; this stops operation but is not an immediate gas leak or fire danger unless you smell gas.

How to Fix Navien Code E001

Step 1: Locate your gas shutoff valve (typically a yellow lever or valve on the gas line near the unit). Ensure it is fully turned to the 'on' position (parallel to pipe). Do not touch any internal parts.
Step 2: Press and hold the red or black reset button for 3 seconds, then release. Wait for the unit to attempt a restart. If it clears and runs, you're fine for now.
Step 3: If the code returns, or if you smell gas at any point, turn the gas off at the valve, open windows, and call a licensed HVAC pro. Do not attempt to clean the flame sensor or burner yourself.

How to Reset Navien Code E001

Turn off the unit using the power button on the front panel.
Turn off the gas supply valve.
Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
Restore power at the breaker, then open the gas valve.
Turn the unit back on. If the error returns, the underlying issue needs repair.

What does E001 mean?

Error code E001 on a Navien unit means the ignition control module tried to light the burner but didn't detect a flame within the safety timing window (typically 10-15 seconds). This is the most common lockout on Navien condensing boilers and water heaters, especially in the NCB, NPE, and NHB series. The system will attempt up to five retries before locking out permanently with this code.

The most frequent causes are a blocked flame sensor (a metal rod inside the burner that reads flame current), a fouled burner (from dust or soot), or a failed hot surface igniter (HSI) on newer models. Older NPE models use a spark igniter, so the root cause differs by series. The control board monitors flame current in microamps (µA); if it drops below 0.5 µA after ignition, it shuts the gas valve and logs E001.

Sometimes the issue is simpler: a gas supply problem like a closed shutoff valve, low gas pressure (under 7 inches water column for natural gas), or air in the gas line after a new installation. Navien's multifunction valve (gas valve) includes the regulator, so a bad valve diaphragm can also cause this code—especially on units over 5 years old.

Affected Models

Source Documentation

Manual	Page	Reason	Action
NFB-H Installation & Operation Manual	116	Heat Exchanger Overheat	Check for proper system flow.
Navien NCB-H Installation & Operation Manual	129	Heat Exchanger Overheat	Reset the boiler from the front panel.
Navien NFB-H Installation & Operation Manual	116	Heat Exchanger Overheat	Check for proper system flow.
Navien NFC-H Installation & Operation Manual	127	Heatexchanger over temperature	Manual RESET Auto RESET
Navien NHB-H Installation & Operation Manual	119	Heat Exchanger Overheat	Check for proper system flow.

Recall Notices

Navien Tankless Water Heaters and Combination Boilers Recalled Due to Carbon Monoxide Hazard 19-027

LP gas conversion kits can cause units to produce excessive carbon monoxide.

View official notice

Replacement Parts

Part	OEM Number	Est. Cost
Flame sensor rod assembly	30013785A	—
Hot surface igniter (HSI) - NCB/NHB series	30013792A	—
Multifunction gas valve (complete)	30013178A	—

Related Codes on Same Models

Code	Description	Severity
E003	Abnormal Ignition	Warning
E004	False Flame Detection	Warning
E012	Flame Loss	Warning
E016	Overheating	Warning
E030	Exhaust Overheat Sensor	Warning
E031	Inlet Thermistor Open/Short	Warning
E046	Outlet Thermistor Open/Short	Warning
E047	DHW Thermistor Open/Short	Warning
E060	Fan Motor Abnormality	Warning
E109	Fan Motor Speed Low	Warning