What do Navien error codes E012 and E016 mean?

Navien's error code chart lists E012 as flame loss. The burner lit, and then the flame went out or the heater could no longer confirm it. That separates E012 from Navien E003, which is ignition failure, where the burner never lit at all.

Navien's self-diagnostic actions for E012 are two lines:

1. 1Clean the intake air filter. Navien says the filter sits at the top left of the water heater, behind the front cover.
2. 2Make sure the electrical cord is properly grounded.

Those two items show where Navien points first for flame loss: air and electrical ground. Rinnai's service manual, for comparison, lists the same family of causes for its own flame failure code, including restricted air and exhaust and a poor ground, and says a properly grounded circuit is critical for flame sensing.

### How do I clean the intake air filter?

Navien's manual says a clogged intake air filter will cause the heater to stop operating, and that the air intake filter should be cleaned every three to four months. The steps in the manual run like this:

1. 1Press the Power button on the front panel to turn the heater off.
2. 2Disconnect the power supply to the water heater.
3. 3Remove the front cover.
4. 4Remove the screw that secures the air intake filter, at the top left.
5. 5Pull the filter out, remove it from its plastic frame, and clean it with a toothbrush and clean running water.
6. 6Let the filter dry completely before putting it back.
7. 7Reassemble, replace the front cover, reconnect the power and turn the heater on.

If you are not comfortable with any of that, leave it to a technician. It involves the front cover and the power supply, and it is not a job to guess at.

E016 is overheating of the heat exchanger. Navien's chart gives three actions, in this order:

1. 1Turn off the system for at least 30 minutes, and then restart it.
2. 2Clean the cold water inlet filter.
3. 3Flush the heat exchanger.

The heater is protecting itself. Something is keeping the heat exchanger from shedding its heat into the water, and the control board shuts the burner down. The restart step gives it time to cool. The filter step checks that water is flowing freely into the heat exchanger. The flush step removes mineral buildup inside it.

Navien's E030 code, exhaust overheating, appears in the same chart. It is set off when the flue temperature passes 149 degrees Fahrenheit, and Navien lists the same three actions for it.

### How do I clean the cold water inlet filter?

Navien's manual describes draining the heater first. You turn the Power button off, close the gas valve, close the water supply valve to the heater, and open the hot water faucets so the lines drain. Then you remove the cold water inlet filter, rinse it with clean cold running water, scrub it with a brush if needed, reinstall it and tighten it, and refill the heater. On A model units there is also a recirculation inlet filter to clean the same way.

A partly clogged inlet filter can also cut your hot water flow, so the payoff is bigger than the error code alone.

### Should I flush the heat exchanger?

Navien lists it for E016, and Phoenix has hard water, which leaves mineral scale wherever it is heated. Navien's manual, though, calls the flush "a somewhat complicated procedure," and says improper maintenance can void your warranty. It calls for a five gallon bucket, diluted cleaning solution, three hoses and a circulation pump, and the solution circulates through the heater for at least 45 minutes. Navien says to contact an authorized technician or licensed professional if you are uncertain about any of the steps.

Our page on how often to descale a tankless water heater in Phoenix covers how often it should happen here. If your heater has never been flushed and it is showing E016, this is the step most worth paying a professional to do.

### What do the other codes on Navien's chart mean?

E012 and E016 sit in a table of codes in the operation manual. A few neighbors are worth knowing, using the manual's own labels:

• E004, false flame detection. Navien's action is to make sure the electrical cord is properly grounded.
• E030, exhaust overheating. The same three actions as E016.
• E109, abnormal fan motor operation. Clean the intake air filter.
• E110, abnormal air pressure. Make sure the exhaust pipe is free of obstructions, and clean the intake air filter.
• E046, E047 and E060, which are limit control, exhaust thermostat and dual venturi faults, and the thermistor codes such as E407, E421 and E432. For these, Navien says to contact Technical Support at 1-800-519-8794.

The pattern is that Navien hands you a filter or a ground to check for the simpler codes, and hands the rest to a professional.

Do not keep resetting. Navien says resetting the heater with the Reset button may clear a minor problem, and points you to Technical Support at 1-800-519-8794 if it does not. A code that returns after the filter cleaning, the grounding check and a flush is no longer a maintenance item.

For E012, that means a technician measures inlet gas pressure while the heater fires. Navien's installation manual gives the range as 3.5 to 10.5 inches of water column on natural gas and 8.0 to 13 inches on propane, and says measuring it should be done by a licensed professional only. They also check the flame rod and igniter, the vent, and the ground.

For E016, it means testing the temperature sensors, the water flow, and the condition of the heat exchanger itself.

That comes first, before any code. If you smell gas, do not use switches or a phone inside, and do not try to light anything. Leave the building with the doors left open behind you, and phone 911 and Southwest Gas at 877-860-6020 once you are outside.

Call when E012 or E016 returns after you have cleaned the filters and checked the ground, when the heater will not restart, when the inlet filter is full of debris that suggests scale in the lines, or any time you are not sure about a step. HQ Plumbing and Air is licensed and insured, and takes emergency calls 24/7. The estimate is free and the price is upfront.

If your heater shows a different code, our pages on Navien error code E003 and Rinnai error code 12, the flame failure code on a Rinnai, cover the neighbors of E012. When a tankless heater is getting old and the codes keep stacking up, see our page on whether to repair or replace a water heater.