Navien Tankless Water Heater Ignition Failure

Navien Tankless Water Heater Ignition Failure [Solved]

Ignition failure on a Navien tankless water Heater occurs due to gas supply issues, bad flame rod, insufficient gas pressure, and faulty gas pressure regulator. 

Your water heater will notify you by throwing the error code E003 if there is a problem with ignition. 

In this guide, I will break down every culprit responsible for ignition failure. So, keep reading to discover the solution to this issue. 

Table of Contents

I will unfold 4 reasons that can cause the ignition issue. Plus, I will walk you through the troubleshooting steps to fix the ignition problem. 

01. Gas Supply Issue

Ignition failure is the result of not getting sufficient gas supply to the combustion chamber. Without fuel, you can’t expect your water heater to fire up. 

No gas can flow to the unit if the main gas control valve is in the off position. Turns out, having insufficient fuel in the gas tank can prevent the tankless water heater from igniting. 

Nonetheless, you can never turn on your water heater if you don’t plug it into a properly grounded electric outlet. 

How To Fix: 

Check the gas control valve position on the gas line. Ensure you turn the gas valve counterclockwise to let the gas flow to the unit freely. 

Next, you should verify there is enough gas in the gas tank. If it’s empty, you must refill it with fuel. 

Lastly, verify you plug your tankless unit into a properly grounded outlet. If the outlet is at fault, I highly recommend you call a certified electrician to solve this issue. 

02. Faulty Flame Rod

Without a functioning flame rod or igniter, it’s impossible to ignite the unit. Over time, the flame rod gets covered with gas residue or burnt out. As a result, it will not work to fire up the unit. 

Besides, if the flame rod gets bent or damaged, you can’t ignite your tankless water heater. 

Regarding this, you should either clean the flame rod or replace it to bring the water heater back into normal operating condition. 

How To Fix: 

Start with inspecting the flame rod. In this case, remove the front cover panel first. Then, locate the flame rod, which you can find under the blower fan. So, unscrew the blower fan and slide it out. Next, disconnect the flame rod wiring and pull out the flame rod. 

If it’s dirty, you must clean it with an emery cloth. On the other hand, if it gets cracked or broken, you must replace it with a new one. 

Don’t forget to inspect the flame rod wiring. A damaged wiring at the flame rod will provide wrong signal to the controller, which causes the unit to not ignite. 

03. Bad Gas Pressure Regulator

A faulty gas pressure regulator can also be a culprit that causes ignition failure. If the gas pressure regulator fails to keep up with the flow rate, the unit will not receive sufficient gas pressure for proper ignition. 

How To Fix: 

If you are not handy, don’t mess up with gas. It will be best to leave the inspection task for professionals. In short, call a certified plumber to examine the gas pressure regulator. Don’t hesitate to replace it if it’s at fault. 

04. Insufficient Gas Pressure

Your Navien Tankless Water Heater requires sufficient gas pressure for proper operation. If the gas pressure is insufficient, you can’t ignite the water heater. To operate the water heater, the gas pressure should be as the following table: 

Gas TypeMinimum PressureMaximum Pressure
Natural5” WC10.5” WC
Propane8” WC13.5” WC

How To Fix: 

You must check the gas pressure with a manometer. Follow the below steps to learn how to check gas pressure on Navien Tankless Water Heater: 

  • Shut off the gas supply by turning the gas valve clockwise.
  • Open a hot water faucet for several minutes to purge the air. Then, close the faucet again. 
  • Locate the pressure port on the gas inlet and remove the screw from the port.
  • Connect a manometer to the pressure port and reset it to 0.
  • Open all the fixtures to operate the unit at its maximum burn. 
  • Now, check the manometer and note the pressure reading. It should be as I mentioned in the above chart. 

If the gas pressure goes out of range, you must adjust the gas pressure to meet the requirements. I suggest you call a professional to fix the gas pressure issue. 

How To Reset A Navien Tankless Water Heater

For minor problems, resetting the water heater can fix the issue. 

To reset the unit, you just need to press the Back button on the front panel. Once you press that button, it will automatically reset your water heater. 

You can also hard reset the Navien Water Heater. In this case, just unplug the unit from the electrical outlet and leave it in this state for 30 minutes. Then, plug your water heater into the outlet again, which will reset the tankless water heater. 


Failure to ignite the Navien Tankless Water Heater is frustrating as you will no longer get any hot water because of it. 

You can easily fix the ignition issue if you know the reasons behind it. Fortunately, I already broke down those reasons that caused the ignition problem. So, follow the troubleshooting steps I described to resolve the issue. 

However, if our troubleshooting guide will bring you no luck, I bet your water heater is going through a complex problem. In this case, it will be best to contact a qualified plumber to look at the issue. 

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