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Code 11 is ignition failure.
Ensure that your gas is turned on.
Start by checking the vent system to ensure there is no obstruction or separation in the vent system.
Second I would recommend flushing the water heater with vinegar or Rectorseal Calci-Free. Calcium and scale build up in tankless water heaters can cause several failures that are not directly related to the specific code displayed on the heater.
If the problem persist I would look for a plumber that is familiar with tankless water heaters.

Noritz Water... | Answered on Mar 02, 2019

You should try to describe the noise and what is happening when the noise occurs. Then someone may be able to give you some diagnosis of the problem. For example, does it make a big boom sound went it lights the burners? Then you might need to clean and adjust the pilot light.

Noritz Water... | Answered on Dec 25, 2018

Here is a link to all the Noritz error codes. There is NO Code 67.

Noritz Water... | Answered on Nov 21, 2018

I had the same problem with my Noritz 751M, I called the plumber and after he talked with Noritz and ran a bunch of tests (for $150) he told me I needed a new unit ($4,000 installed). They implied it was my fault cause I never flushed it over 8 years. They were unable to tell me the flow rate though (which should be very low if scale was my main issue). I decided to take over as I am very handy and an engineer. Here is what I found:

1. The unit is 8 years old and was never descaled (orig installer did not install the bypass valves nor tell me to flush annually). So, I installed the valves ($70) and bought a pump/hoses/bucket/Zep CLR ($150) and did the flush. There was tons of flow thru the exchanger (I did not measure how much).

2. I called Noritz myself (they were very helpful) and cleaned up the igniter rod with sandpaper (it was very discolored due to 8 years of sparking). This did the trick and my unit fired up but it was very sporadic (sometimes yes & no). The difficult part is that while the igniter is installed you CANNOT actually see (nor definitively hear) the sparking. It seems like sometimes the spark happens (unit fires right up) and sometimes it doesn't (unit cycles and ends in a Code 11 after a couple of minutes).

3. INFO: Per the field manual (Search google for: docslide.us_noritz-field-manual-2009) you can read the flow rate data from Data #14 on the remote control. It needs to be >0.5 GPM for the sparking to happen which then triggers the gas flow. You can live monitor Data #14 by following the instructions in the field manual on pp.46-47. The startup logic is: Flow > 0.5 GPM then Sparking Happens then the Gas Flows then Flames start in the combustion chamber

4. I got mine to successfully start by loosening the ignitor rod PN 101 and jiggling it while still inserted into the combustion chamber (holding it with insulated pliers while still against the case) - somewhat dangerous and startling when after sparking the gas flows and flaming starts but not too bad.

5. BOTTOMLINE: I got it working but it would not "always" light (even though my flow was always >0.5 GPM). Noritz told me that it is probably because I have the older black ignitor (PN 126 = EHEJ003). They have a new and improved gray ignitor (PN 126 = EMUJ004). I ordered it with a couple of other ignitor parts for a total of $35. I just installed them and they work great - ignition all the time from every faucet.

6. ENDGAME: Order the new ignitor parts, verify your flow rates using the field manual. See the pics below for some insight. I spent 20 hrs troubleshooting and wanted o share. If you want more info just email me at:

You can monitor the flow rate and flame by doing a skype (PC at faucet to Phone place in front of Noritz) - you will be able to see the Noritz turning on (with flow rate displayed) each time you turn on a faucet - it is very helpful for troubleshooting and verification





Noritz 6.3... | Answered on Nov 21, 2018

I need the full model number of the water heater to pull the manual on it for you.... so far only an error code 61 is shown. sometimes a 6 can look like a 5 on a digital display if it's a 6 then error code 61 is bad fan motor or printed circuit board that sends power to the fan motor.Get me the full model number, we can go from there

Noritz Water... | Answered on Nov 13, 2018

Electronics are very sensitive to temp, so I agree with the tech.

Noritz Water... | Answered on Sep 05, 2018

check gas pressure and water pressure

Noritz Water... | Answered on Feb 11, 2018

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