- Boilers
- Tankless gas water heater
E012
Navien E012 on a tankless water heater: flame loss
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
The burner flame went out during operation. Navien's actions are to clean the intake air filter and make sure the power cord is properly grounded. Reset once with the Back button and call a technician if it returns.
Safety first
Stop and check this first
- If you smell gas: do not try to light any appliance, do not touch any electrical switch and do not use any phone in the building. Call your gas supplier from a neighbor's phone and follow its instructions; if you cannot reach it, call the fire department.
- Do not remove the front cover to look inside: Navien warns that operating the heater with the front cover open can cause fire or carbon monoxide poisoning, and that the cover may only come off with the power disconnected.
Safe checks you can perform
- Plug and outlet
- Date of the last intake filter cleaning
- One reset with the Back button
- Intake air filter cleaning
Leave these tasks to a qualified professional
- Do not attempt this professional task: Clean the filter and verify grounding
- Do not attempt this professional task: Measure inlet gas pressure and combustion
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Clean the filter and verify grounding
What they doThe technician cleans the intake air filter and tests outlet grounding.
They must show youthe filter condition and ground test.
In writingboth results.
Measure inlet gas pressure and combustion
What they doWith a manometer at maximum firing rate and a combustion analyzer, the professional checks inlet pressure and gas and air ratio against the installation manual.
They must show youthe readings against the manual.
In writingwhat was adjusted or replaced.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Plug and outlet
- Who:
- you.
- How:
- look at how the heater is plugged in, without touching wet parts. Navien supplies a 3-pronged grounded plug for a grounded outlet.
- Result that matters:
- whether it plugs straight into a 3-hole outlet.
- If there is an adapter or extension:
- tell the technician; grounding must be tested.
- If it plugs straight in:
- continue.
- Evidence to keep:
- photo of the plug.
Evidence: Navien NPE-A2 and NPE-S2 installation and operation manual
Date of the last intake filter cleaning
- Who:
- you.
- How:
- check maintenance records. Navien recommends cleaning the intake air filter every 3 to 4 months.
- Result that matters:
- whether the filter is overdue.
- If it is overdue:
- ask the installer or technician to clean it.
- If it was cleaned recently:
- the filter is less likely.
- Evidence to keep:
- last maintenance invoice.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual
One reset with the Back button
- Who:
- you.
- How:
- press the Back button on the front panel. Navien's manual says resetting may solve the problem when an error appears.
- Result that matters:
- whether E012 comes back.
- If the heater runs normally:
- note the date; if E012 returns later, mention that it was reset before.
- If E012 returns:
- do not keep resetting; Navien says to contact an authorized technician, a licensed professional or its technical support.
- Evidence to keep:
- photo of the code before and after the reset.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual
Intake air filter cleaning
- Who:
- the installer or a technician.
- How:
- with the heater off and the power disconnected, removes the front cover, takes out the filter, cleans it with a brush and running water, lets it dry fully and refits it, as Navien's manual describes.
- Result that matters:
- whether E012 stops after cleaning.
- If it stops:
- note the date.
- If it continues:
- gas pressure and combustion must be checked.
- Evidence to keep:
- photo of the filter before and after.
Navien's user manual lists this as owner maintenance, but it means removing the front cover of a gas appliance. We recommend leaving it to a technician.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual · Navien NPE-A2 and NPE-S2 installation and operation manual
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Navien
- Product type
- Tankless gas water heater
Known code variants
- calentador Navien E012
- Navien 012
- Navien E012
- Navien E012 flame loss
- Navien E012 pérdida de llama
- Navien error E012
What it means
Navien defines E012 as flame loss: the flame was established and then lost while the heater was running. Navien's owner actions are cleaning the intake air filter and ensuring the electrical cord is properly grounded. The filter sits behind the front cover, so we recommend leaving its cleaning to the installer or a technician. Gas pressure and combustion checks are for a licensed professional. The code does not identify a failed part.
Warnings and stop conditions
- Criticalsource verified
If you smell gas: do not try to light any appliance, do not touch any electrical switch and do not use any phone in the building. Call your gas supplier from a neighbor's phone and follow its instructions; if you cannot reach it, call the fire department.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual
- Highsource verified
Do not remove the front cover to look inside: Navien warns that operating the heater with the front cover open can cause fire or carbon monoxide poisoning, and that the cover may only come off with the power disconnected.
Evidence: Navien NPE-A2 and NPE-S2 installation and operation manual
Symptoms and causes
Probable causes · in order
- Clogged intake air filterPossible
Navien's first action for E012; it recommends cleaning the filter every 3 to 4 months. Fits if it has not been cleaned recently.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual
- Grounding problemPossible
Navien's second action. Fits with adapters or outlets of unknown grounding.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual · Navien NPE-A2 and NPE-S2 installation and operation manual
- Gas supply or combustion faultPossible
If filter and grounding are fine, inlet pressure and combustion must be measured by a licensed professional.
Evidence: Navien NPE-A2 and NPE-S2 installation and operation manual
Virtual technician
Does E012 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Navien NPE-A2 and NPE-S2 user's information manual
Navien · 2020 · manual
- 2
Navien NPE-A2 and NPE-S2 installation and operation manual
Navien · 2026 · manual
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