Noritz Code 11

How To Fix Noritz Code 11?

Noritz Code 11 indicates there is a problem with the ignition. 

It means your tankless water heater fails to ignite the burner due to insufficient gas supply, improper inlet gas pressure, spark issues like wire attached to flame rod comes loose, and air supply issues. 

And this troubleshooting guide will walk you through every troubleshooting step to fix those issues I mentioned to reset the code 11. 

Without further ado, let’s dive in. 

Table of Contents

Noritz Code 11: What Does It Mean?

Noritz error code 11 means ignition failure. In other words, the unit doesn’t get sufficient gas supply or sense the flame and the heater fails to ignite. 

Generally, the Noritz water heater throws the error code 11 because of insufficient gas supply, improper gas pressure, and dirty flame sensing rod. 

Turns out, electric supply issues like a failed circuit board and loose wiring to the flame sensing rod are accounting for the error code 11. 

Below, I will explain all the reasons responsible for the fault code 11 and provide their solutions as well to erase that code. 

1. Insufficient Gas Supply

Like every gas appliance, Noritz Tankless Unit also requires a continuous gas flow to the burner for proper combustion. If you receive no gas to the burner, you can’t ignite it. Sufficient amount of gas will not flow to the unit if: 

  • You don’t fully turn on the gas valve
  • Install the gas meter improperly 
  • Bad gas regulator
  • Size up the gas lines improperly

How To Fix: 

Begin with inspecting the position of the gas valve and ensure you fully turn it on. If you don’t fully turn on the gas valve or it’s Off, open the gas valve completely by turning it counterclockwise. 

Sizing up the gas line improperly is another common reason that causes the unit to not get enough gas for complete combustion. I highly suggest you check the gas line and ensure you size it up according to the manual. 

In addition, make sure the gas meter you install is sized up properly for the unit and other gas appliances. Use a gas meter that can supply the entire BTUs for the unit and other gas appliances in the building. 

And last not the least- ensure the gas regulator you install is functioning properly. If not, you should replace the gas regulator. In this case, I recommend you call a certified technician to do this task for you.  

2. Improper Inlet Gas Pressure

The inlet gas pressure of a functioning tankless water heater should be as the following chart: 

BTU Input of UnitNGLP
Up to 199k4” to 10.5” WC8” to 14” WC
Over 199k5” to 10.5” WC10.5” to 14” WC

If the inlet gas pressure is going lower than the value you see on the chart, you can’t ignite your Noritz Tankless Water Heater. 

How To Fix: 

You must measure the inlet gas pressure to verify the pressure is within specifications. To check the inlet gas pressure, you should have a Phillips head screwdriver and a digital manometer. 

At the first step, shut off the gas valve. Then, use the Phillips head screwdriver to remove the screw from the inlet test port. 

Removing the screw from the inlet test port
*Removing the screw from the inlet test port*

Next, connect the hose of the digital manometer to the port by sliding it over the test port. 

Attached manometer hose to the inlet test port
*Attached manometer hose to the inlet test port*

Now, turn the gas valve counterclockwise to open it and the manometer will show the static gas pressure, which is actually the gas that is not being used. 

Then, check the dynamic gas pressure and this is the pressure when gas is being used by opening up a few hot water fixtures. 

Both the static and the dynamic gas pressure should stay above the minimum requirements of the unit. If both the pressure is below the minimum requirements, ensure: 

  • You size up the gas line properly
  • The gas meter or regulator you install can handle the total BTU load of all gas appliances. 
  • If you live in California, ensure the earthquake shut-off valve doesn’t get tripped.

3. Dirty Ignition or Flame Sensing Rod

Dirty ignition rod or flame sensing rod

A dirty ignition rod can also prevent the unit from igniting. Over time, the ignition rod gets coated with carbon deposits. 

As a result, the ignition rod or flame sensing rod can’t detect a flame or prevent a spark from happening. And guess what, it causes the unit to flash the error code 11 on the controller display.  

If you want the ignition rod to produce a spark again, you must clean the ignition rod. You can clean the rod with a 100-grit sandpaper. 

Fortunately, I wrote a guide on Noritz Tankless Water Heater Maintenance where I described how to clean the ignition or flame sensing rod. So, you can check that article out. 

However, if cleaning the ignition rod will bring no luck for you, I bet the ignition rod gets defective. In this case, you must replace it with a new ignition rod. 

4. Spark Issues

Three things like air, gas, and spark are needed for proper ignition or combustion. If any of these are missing, you can’t ignite your Noritz Water Heater. 

Spark is one of the three elements that is a must for ignition. No spark will occur if the high voltage cords are at fault. Turns out, a failed circuit board will not send any voltage to the igniter. Consequently, the igniter fails to ignite the burner and pops up the error code 11. 

Additionally, if the blue wire connected with the flame rod comes loose, it will cause the ignition problem. 

How To Fix: 

I recommend you start from the element where the spark actually occurs. It will require a bit of elimination like disassembling the ignition rod assembly. I hope you will find the culprit before looking at the circuit board. 

It would be best to call a certified technician when it comes to inspecting the circuit board or wiring issues. 

Lastly, verify the blue wire attached to the flame rod is secure and tight. 

5. Air Supply Issue

As I mentioned, you also need air to make a complete ignition. If the unit doesn’t get sufficient air into its burner, it won’t ignite the burner. 

If the burner gets clogged, it may prevent the air from going into the burner chamber. Besides, dirty air screen filters or clogged exhaust vents can also cause this air supply problem. 

How To Fix: 

I highly suggest you inspect the air screen filter, exhaust vent, and the burner periodically. If needed, clean them. 

In this case, this guide on Noritz Tankless Water Heater Maintenance will help you remove dirt or lint from those heater elements. 

Apart from these, you can remove the front cover from the unit. It will help you get all the combustion air the unit needs for proper combustion. 

How Do I Fix Noritz Code 11?

To erase the Noritz trouble code 11, go along with the following steps: 

  • Discover the reasons that cause the unit to pop up the error code 11 (I already discussed them above)
  • Once you figure out the culprit behind this code, resolve the issue. 
  • Finally, reset the unit to remove the error code from the controller display. 

If you don’t know how to reset the tankless unit, check out this article on Noritz Tankless Water Heater Reset Button. 


I bet this step-by-step troubleshooting guide will help you erase the error code 11. Just follow the steps I mentioned and resolve those issues. Finally, reset the unit to remove the diagnostic code from the display. However, if you need further assistance, don’t hesitate to reach out to the Noritz Support team at 866-766-7489. 

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