What do Navien tankless error codes mean?

This chart follows Section 5.2 of Navien's operation manual for the NPE series, which covers the NPE-180A, 210A, 240A, 150S, 180S, 210S and 240S. Other Navien lines, including combination boilers, use their own charts, so check the manual for your model.

Navien's technical support number in the manual is 1-800-519-8794. The manual adds that if none of the listed remedies resolves the problem, you should contact an authorized technician, a licensed professional or technical support.

About ten of the codes on the chart come with a step an owner can safely take. Start with the gas smell rule. If you smell gas, do not light anything, do not touch a switch or use a phone inside, and leave. Southwest Gas takes emergency calls at 877-860-6020, and 911 works for any suspected leak.

With no smell:

• E003. Confirm the gas valve at the heater is open. Our page on Navien error code E003 goes through the rest of the ignition checklist.
• E004, E012 and E515. Navien points to the grounding of the electrical cord. That means a correct three prong outlet, and an outlet or cord that is not damaged or loose. Wiring changes are for an electrician or a technician.
• E012, E109 and E110. The intake air filter. Navien's manual says a filter clogged by dust or lint will stop the heater, and that the filter should be cleaned every three to four months. Our page on Navien error codes E012 and E016 has the cleaning steps.
• E110. Also make sure the exhaust pipe is free of obstructions. Check the vent termination outside.
• E016 and E030. Turn the heater off for at least 30 minutes. Then clean the cold water inlet filter and, if the heater has not been flushed, arrange a flush.
• E438. The circulation pump code. Navien says to make sure all the water supply and return lines are open on an external recirculation system.
• E760. This is not a fault. It is a reminder that routine service and a flush are due.

Everything else on the chart points to technical support. Those are thermistors, valves, sensors, the circuit board and communication faults, and none is an owner repair.

### Is E110 really about the air filter?

Yes, and Navien says so in two places. The chart lists E110 as abnormal air pressure and tells you to check the exhaust pipe for obstructions and clean the intake air filter. The maintenance section explains that if dust or lint clogs the air intake filter, the heater stops operating and the display shows the 110 error code. The filter sits at the top left of the heater, behind the front cover, and Navien recommends cleaning it every three to four months. The installation manual also warns against installing the heater where dust and debris collect or where hair sprays, spray detergents or chlorine are used, and says the owner is responsible for keeping the exhaust and intake terminations free of blockages.

### How do I reset a Navien?

Navien's manual says that if an error message appears, you can try resetting the heater by pressing the Reset button on the front panel. For minor problems that may clear the issue. If the code returns, follow the troubleshooting chart or contact technical support. Repeated resetting does not fix a fault. It hides the display.

### What is the difference between the A and S models?

The chart applies to both. The A models have Navien's internal recirculation pump, which is why E438 mentions an internal pump and a 2 way valve. The A models also have a recirculation inlet filter to clean along with the cold water inlet filter. Recirculation on the S models runs through an external pump.

These three codes point at the heat exchanger, and Phoenix has hard water, which leaves mineral scale wherever it is heated. Navien's manual calls the flush "a somewhat complicated procedure," says improper maintenance can void the warranty, and tells the owner to contact an authorized technician if unsure. Our page on how often to descale a tankless water heater in Phoenix gives the schedule, and our page on how hard water damages plumbing explains why it forms.

Navien makes several product lines, and older units or other lines use different codes and different steps. The rating plate gives the model number, and the manual for that model is the right chart. If the code on your display is not on the list above, treat it as a call for service.

Call for any code that comes back after one reset, any code that says to contact technical support, an E016 or E030 on a heater that has never been flushed, or any time you smell gas. We are licensed and insured, take emergency calls 24/7, and quote upfront after a free estimate. Before you reset anything, it helps to read the saved list of past errors; how to view or clear the Navien error history explains where it is.

If your heater is a different brand, see our pages on the Rinnai code list, Rheem tankless codes and A. O. Smith tankless codes. If codes keep stacking up on an older heater, our page on whether to repair or replace a water heater can help you weigh it.