Navien Error Code E012: Flame Loss and What to Check
Quick answer: Navien E012 is the error code that means “flame loss.” The burner lit, then the flame went out or the heater stopped sensing it, so the control shut off the gas. Navien’s user manual lists two owner-level checks: clean the intake air filter and make sure the electrical cord is properly grounded. Confirm the gas supply valve is open, press Reset once, and if E012 returns, arrange service. Flame loss can involve gas pressure, the flame rod, the venting, or the gas valve, and none of those are owner repairs.
No code on the display, and the water is just lukewarm? See tankless water heater not heating.
Safety first: If you smell gas, Navien’s instructions are to not light any appliance, not touch any electrical switch or phone in the building, and call your gas supplier from a neighbor’s phone, or the fire department if you cannot reach the supplier. Do not adjust the gas valve, do not remove the front cover with the heater powered, and do not keep resetting a heater that keeps losing its flame.
In this guide
What Navien E012 means
Navien’s NPE user’s information manual lists E012 as Flame loss. The heater ignites normally, and then the flame signal drops during operation. The control treats that as unsafe and closes the gas valve. This is different from E003, Ignition failure, where the burner never lights, and from E110, abnormal air pressure, where the airflow reading is wrong before or during the burn.
Flame loss has several possible causes. Some are simple, such as a dirty intake air filter starving the burner of air, or a grounding problem that disturbs the flame-sensing circuit. Others, such as low gas pressure during high demand or a worn flame rod, need measurement and parts.
Owner-level checks from the Navien manual
- Confirm the gas supply. Check that the gas shutoff valve at the heater is open (handle in line with the pipe). If other gas appliances in the home have also stopped, or a propane tank is low or empty, the problem is the supply, not the heater.
- Clean the intake air filter. This is Navien’s first listed remedy for E012. The manual’s procedure is to turn the heater off with the Power button, disconnect the power supply, remove the front cover, remove the screw holding the filter, pull the filter out, clean it with a toothbrush under running water, let it dry completely, refit it, replace the cover, reconnect power, and press Power. Use the steps in your own manual, since the filter’s location varies by model.
- Check the grounding. Navien’s second listed remedy is to ensure the electrical cord is properly grounded. For an owner that means confirming the heater is plugged into a three-prong grounded outlet and not running through an adapter or an extension cord. Testing the ground itself is an electrician’s job.
- Press Reset once. Navien’s manual says an error message can sometimes be cleared by resetting the water heater. If E012 clears and does not return, note the date.
- If it returns, stop. Navien’s instruction is to contact Technical Support (1-800-519-8794 in the U.S.) or your installer if the remedies do not resolve the problem. A heater that repeatedly loses its flame has a fault that resets will not fix.
What a technician looks at for E012
| Area | Why it causes flame loss | Why it is not an owner job |
|---|---|---|
| Gas pressure under load | Pressure that drops when the burner goes to high fire, or when other appliances run, starves the flame | Measured with a manometer at the gas valve with the heater running |
| Flame rod | A rod with deposits, a loose connection, or damaged wiring stops sensing the flame even though it is burning | Behind the front cover next to the burner; needs cleaning or replacement by a technician |
| Venting and intake air | Exhaust recirculating into the intake, or a restricted intake, makes the flame unstable | Vent joints and lengths are checked against the installation manual |
| Gas valve and ignition components | A gas valve that does not hold open, or an ignition fault, drops the flame mid-cycle | Internal gas components; Navien says not to repair or replace parts unless the manual specifically says so |
| Power supply and grounding | Voltage drops or a poor ground interfere with the flame-sensing circuit | Needs an electrician to test the circuit and ground |
E012, E003, and E110: which one you have
| Code | Navien’s name | What happens | Navien’s first owner check |
|---|---|---|---|
| E003 | Ignition failure | Burner does not light | Ensure the main gas supply valve is open |
| E012 | Flame loss | Burner lights, then flame goes out | Clean the intake air filter; check grounding |
| E110 | Abnormal air pressure | Airflow reading out of range | Check exhaust pipe for obstructions; clean the intake air filter |
If your heater alternates between E012 and E110, tell the technician; a venting or condensate problem can produce both. See the condensate trap guide if there is water under the unit.
What to tell the technician
- Full model and serial number from the rating plate, and whether the unit runs on natural gas or propane.
- When E012 appears: at the start of a draw, after several minutes, or only when more than one hot tap is running.
- Whether other gas appliances are affected, and whether a propane tank was recently filled or is low.
- What you found at the intake filter, how the heater is plugged in, and whether a reset cleared it and for how long.
- Any recent vent work, remodeling near the heater, or a new gas appliance added to the home.
Frequently asked questions
Can low gas pressure cause E012?
Yes. Pressure that is fine at idle can drop when the burner goes to high fire or when a furnace or range runs at the same time. A technician measures inlet pressure under load to confirm it.
Should I clean the flame rod myself?
No. The flame rod sits beside the burner behind the front cover. Navien’s manual says not to repair or replace any part unless the manual specifically recommends it, and flame-rod cleaning is not on the owner list.
Is E012 dangerous?
The code is the heater closing the gas valve because it cannot confirm a flame, which is the safe response. The risk is in repeatedly resetting it or bypassing it. Treat a recurring E012 as a service call.
Why does E012 happen only when two showers run?
That pattern points to gas supply under load: the burner goes to high fire, demand on the gas line rises, and pressure drops below what the flame needs. Tell the technician exactly when it happens.
References: Navien NPE2 series user’s information manual (error code table, intake air filter cleaning, reset, safety information) · Navien NPE operation manual. Your model’s own manual takes priority.
Published October 16, 2026. Written and edited by Jordan Hale. General educational guidance; follow your exact model instructions and use a qualified technician for gas, flame-sensing, and electrical work.
