How do I clear the error history on a Navien tankless water heater?

It sits behind the front panel buttons and holds the ten most recent errors. On the newer NPE panel with a Menu button, Navien's installation manual says to press Menu and choose "3. Error History." On the NFC-H and NCB-H series the entry is "4. Error History." Navien describes the list the same way on each: "A list of 10 recent errors are displayed on the screen, with the most recent error displayed at the top of the list." On the NPE you use Up and Down to move through it and OK to open one entry for detail.

Older units with Info, Reset, Plus and Minus buttons work differently. Navien's NCB-150E service manual says to "press the [Info] button for over 2 seconds to access the error history mode." It adds "A total of 10 errors are stored in memory," numbered 0 to 9, with 0 the most recent.

Whichever panel you have, read the list first. Note the code numbers and how often each one appears. A single E003 from the day the gas was shut off for a repair is a different story from E003 every morning.

On the older panel, yes, and Navien's service manual spells it out. While you are in error history mode, holding the Reset button for 5 seconds shows CLR on the display, and the service manual says this "deletes all the ERROR HISTORY DATA." Press Reset once to return to normal operation. The NPE-180A service manual's button chart lists a long Reset press for individual deletion of error history and tech data, and its display chart shows CLR as the indicator "Displayed when deleting the Error History or Tech Info."

On the newer NPE panel, the picture is different. The installation manual we checked describes viewing the list and stops there. We found no step to delete it in that manual, or in the NFC-H or NCB-H manuals. So do not expect the older button trick to work on a Menu panel, and do not guess at button combinations. If you need the log cleared on a newer unit, ask Navien Technical Support at 1-800-519-8794 or a Navien-trained technician.

One note on sources. Navien's service manuals are written for technicians, and the copies we read are hosted on ManualsLib. Check the manual for your exact model before you press anything.

They clear the error on the screen right now, not the list behind it. The NPE operation manual says "If an error message appears, you can try resetting the water heater to resolve the problem. To reset the water heater, press the Reset button." On the newer NPE panel the installation manual says "To reset the water heater, press the Back button."

Some errors clear themselves. Navien says "Level 1 errors are automatically cleared when the problem is resolved," and that pressing Back will "clear a level 1 error. The error is then cleared if the problem has been resolved." Note the condition: pressing the button does nothing lasting if the fault is still there.

If resetting does not fix it, Navien says to "refer to the Troubleshooting section of this manual or contact Technical Support at 1-800-519-8794." Pressing Reset over and over is not a repair.

Factory Reset is not a log eraser. On the NPE menu panel it is an installer menu item that Navien describes as "Initialize all parameter settings (panel and main controller) to factory default." The installer menu is password protected, and Navien says it must be set by a qualified professional "with an extensive understanding of the water heater system." Navien adds that "Setting parameters improperly may lead to property damage or injury." Wiping every parameter can undo settings a technician chose for your house, and the manual never says it empties the error list.

You may also see WAIT or a DHW wait message in searches. In the manuals we read, neither is an error code. The NPE-180A service manual's display chart lists WAIT as an indicator "Displayed while waiting for a response from the main controller when executing a command." And DHW Wait Time appears only in the NFC-H series installer parameters, where Navien says "Set the DHW wait time." The manual gives the range as 0 to 20 minutes and the default as 3 minutes. It does not spell out more, so we will not guess. Ignition failure, the other message people search, is Navien error E003. See Navien error code E003 for that one.

Usually leave it. A ten-entry list is the first thing a technician can use to see whether one code keeps coming back. That is reasoning, not a Navien rule, but an empty history throws away the clue.

If you do clear the list on an older panel, write down or photograph the codes first. The heater keeps only ten errors, so a problem that comes and goes over months can push its earliest clues out of the list on its own, and a deliberate clear removes them all at once.

Here is what Navien's NPE chart lists for the codes people see most:

• E003, ignition failure: "Ensure that the main gas supply valve is open."
• E012, flame loss: "Clean the intake air filter."
• E016, overheating of heat exchanger: "Turn off the system for at least 30 minutes, and then restart it."

Our pages on Navien error codes E012 and E016 and what Navien tankless error codes mean go further, and how often to descale a tankless heater in Phoenix covers the flush behind E016.

Call a licensed plumber when the same code returns after a reset, when the code has no listed remedy, or when you smell gas. On gas, Navien's manual is blunt: "Do not try to light any appliance." It also says "Do not touch any electric switch; do not use any phone in your building." Leave the house and call your gas supplier. Navien states "Installation and service must be performed by a qualified installer, service agency or the gas supplier," and that the installation "must conform with local codes." Gas piping, venting and burner work is not a homeowner job, and local code, including any permit and inspection your city requires, applies to it.

HQ Plumbing & Air is licensed and insured, and our water heater service covers tankless units. We give a free estimate, the price is upfront before work starts, and we take emergency calls 24/7. Bring the error history with you, and we start in the right place.