Noritz Tankless Water Heater Error Codes [A Complete List]

This is a complete guide on Noritz Tankless Water Heater Error Codes. In this article, what I will break down: 

• How do you check the error codes history? 
• Explain every Noritz Error code and their solutions
• How do you reset the Noritz Water Heater?

Without further ado, let’s dive in. 

Table of Contents

• How To Check Noritz Error Codes (History)? 
• Noritz Tankless Water Heater Error Codes [A Complete List]
  • Noritz Tankless Water Heater Error Code 11
  • Noritz Tankless Water Heater Error Code 12
  • Noritz Tankless Water Heater Error Code 14
  • Noritz Tankless Water Heater Error Code 16
  • Noritz Tankless Water Heater Error Code 20
  • Noritz Tankless Water Heater Error Code 29
  • Noritz Tankless Water Heater Error Code 45
  • Noritz Tankless Water Heater Error Code 51
  • Noritz Tankless Water Heater Error Code 63
  • Noritz Tankless Water Heater Error Code 66
  • Noritz Tankless Water Heater Error Code 67
  • Noritz Tankless Water Heater Error Code 71
  • Noritz Tankless Water Heater Error Code 73
  • Noritz Tankless Water Heater Error Code F76
  • Noritz Tankless Water Heater Error Code 90
  • Noritz Tankless Water Heater Error Code 91
• How Do You Reset A Noritz Tankless Water Heater?
• End-Note

How To Check Noritz Error Codes (History)?

Before breaking down the meaning of error codes, I will explain how to check the error code history on a typical Noritz Tankless Water Heater. 

1. To begin with, press the Power (on/off) button on the remote controller to turn off the remote. 

2. Now, press both the Up and Down arrows at once until 03 code pops up on the display. 

3. Then, tap on the Down arrow button, which will take you to the error code history. Error codes will be stored in maintenance monitors 91 through 98. And you can see the most recent error code followed by 91. 

4. Press the Up button to check the next error code. 

5. Keep pressing the Up button until you see 000 on the display. 

6. Once you see the 000, press both the Up and the Down buttons together until the display goes blank. 

7. Finally, tap on the Power (on-off) button to turn on the remote.

Noritz Tankless Water Heater Error Codes [A Complete List]

From this chapter, you can learn about the meaning of every error code and the action you need to take to erase that code. 

Noritz Tankless Water Heater Error Code 11

The error code 11 means there was an ignition failure. It’s a result of insufficient gas supply, insufficient airflow, or dirty ignition rod assembly. Because of these reasons, the unit fails to ignite the unit and triggers the fault code 11 on the controller display. 

How To Fix: 

Fortunately, I wrote a complete guide on Noritz Code 11 where I break down everything you need to know to erase that code. So, it will be worth checking that article to fix the gas supply issue and clean the dirty ignition rod.

Noritz Tankless Water Heater Error Code 12

A weak flame or flame loss will cause the unit to throw the error code 12. In simple words, your tankless water heater detects the flame but it gets extinguished during operation. 

Generally, the weak flame will occur because of the same reasons I mentioned for the error code 11 like improper inlet gas pressure, dirty flame rod, and blocked exhaust vent. 

Additionally, venting the unit improperly or the earthquake shut-off valve gets tripped can also cause the unit to flash the error code 12.

How To Fix: 

I already wrote a detailed guide on Noritz Code 12 where I disclosed everything you need to know to erase that code. So, it’s highly recommended to check that article.

Noritz Tankless Water Heater Error Code 14

A thermal fuse failure is what the error code 14 indicates. 

The thermal fuse is basically a safety device that you can find wrapped around the four sides of the copper heat exchanger. This device clips on the front and the back that hold it in place. 

If the external temperature of the heat exchanger reaches dangerous levels, the thermal fuse will break and shut down the unit right off the bat. 

Now, the question you may ask is- what’s the reason behind thermal fuse failure? 

It’s the scale buildup (due to excessive water hardness) in the heat exchanger. This scale buildup acts as an insulator and reduces the transfer of heat from the burner into the water. And the reduced heat transfer means the surface temperature of the heat exchanger rises significantly. 

Eventually, it will get to a point where the surface temperature gets too hot. As a result, the thermal fuse breaks itself to prevent further damage and ends up with displaying the error code 14. 

How To Fix: 

Start with testing the thermal fuse, which is pretty straightforward. Just get a digital multimeter and disconnect the two thermal fuse connections from the unit. 

Now, use your multimeter to test the continuity of the thermal fuse. Usually, the multimeter will make a beeping sound if there is continuity. 

If the multimeter doesn’t make the beeping noise, you must replace the thermal fuse. 

But the proper maintenance to fix the error code 14 is to replace the heat exchanger along with the thermal fuse. 

Yeah, cleaning the heat exchanger can also fix this issue. But if you fail to clean the heat exchanger effectively, the error code 14 will return again. So, it’s highly recommended to replace both the heat exchanger and the thermal fuse. 

The best suggestion I can give you to prevent the error code 14 is to maintain your Noritz Tankless Water Heater. Here maintenance means to treat the water you get or descale the unit annually. 

Noritz Tankless Water Heater Error Code 16

This diagnostic code will appear on the controller display when the outlet water temperature abnormally jumps to a high value. When this occurs, the unit itself will restrict the water flow to avoid further damage.

The following reasons are responsible for the unit to pop up the error code 16:

• The heat exchanger gets clogged by scale deposits
• Feeding the unit with improper type of gas
• Adjust the manifold pressure improperly 

How To Fix: 

First off, inspect the heat exchange for blockage. If needed, flush the heat exchanger or descale the unit to remove deposits from the heat exchanger. 

Fortunately, I wrote an article on Noritz Tankless Water Heater Maintenance, where I described every step to descale the unit properly. 

Next, ensure you fuel up your water heater with the correct type of gas. Check the rating plate of the unit and feed it what gas type the unit requires for proper operation. 

Finally, ensure you adjust the manifold pressure according to the manufacturer guideline. For further assistance, I recommend you call the support team of Noritz at 866-766-7489. 

Noritz Tankless Water Heater Error Code 20

A tripped high limit switch will cause the fault code 20. 

Like the thermal fuse, it’s also a safety feature on a Noritz Tankless Water Heater. When the water temperature rises above the safety level like over 176F to 205F, this switch will trip and cut the electric supply off to the unit. 

In short, the high limit switch will get tripped and shut the unit off immediately to avoid further damage. 

A clogged heat exchanger is the primary reason that causes the unit to trip the high limit switch. It happens because the scale buildup in the heat exchanger reduces the heat transfer into water. 

And guess what, this reduced heat transfer will cause other parts of the unit to retain heat and be responsible for overheating. 

Apart from the dirty heat exchanger, blockage in the venting and a loose wiring connection of the high limit switch will also be responsible for this issue. 

How To Fix:

To reset the error code 20, you need to hard reset the water heater. Just unplug the unit from the electrical connection, wait until the water heater cools down, and plug the unit again. 

Keep in mind; the error code 20 will eventually come repeatedly if overheating is the root cause of this issue. In other words, you need to descale the unit first. Check the following tutorial to learn how to descale the unit: 

Turns out, ensure there is no blockage in the venting and the wiring of the high-limit switch is secure. 

Noritz Tankless Water Heater Error Code 29

If you own a condensing unit from Noritz, you can see the error code 29 because of a problem with the condensate drainage. 

The condensate will not drain freely through the condensate drain line if it’s smaller than ½” inner diameter from the unit. 

Turns out, a frozen condensate drain line will cause the unit to pop up the error code 29. 

How To Fix: 

Ensure the condensate drain line you install is not smaller than ½” inner diameter from the unit. Above this, the drain line should be short, direct, and sloped to the end drain point. 

On the other hand, you must route the drain line to another way where it’s risk-free from getting frozen. 

Noritz Tankless Water Heater Error Code 45

This error message is uncommon on almost every Noritz Tankless Unit but common on NRCP and CB models. When the unit detects an internal water leak, the error code 45 will be triggered.  

How To Fix: 

Check the well and leak sensor as a troubleshooting step to look for a sign of water leak. To get the well and leak sensor, you should remove the front cover. Then, remove the circuit board to expose the leak sensor. 

You need to replace the part if you find the source of the leak. Drying out the well and sensor with a towel is another trick that will come handy. 

If you find no signs of leak, it could be the condensation formed in the light of temperature differences between the components of the unit and the environment. 

To get technical support from Noritz, don’t hesitate to call 866-766-7489.  

Noritz Tankless Water Heater Error Code 51

The error code 51 will blink on the remote controller display if the gas manifold solenoid is at fault. 

It’s a bit of a complex problem and I don’t recommend you do it yourself. Anyway, you can check the gas manifold solenoid valve connection as a basic inspection. 

But the best bait is to call the Noritz technical support team at 866-766-7489 for further assistance.   

Noritz Tankless Water Heater Error Code 63

According to Noritz, the error code 63 stands for a problem with the recirculation circuit. But it’s a bit misleading. 

When you bleed the recirculation system as per manual instructions, the diagnostic code 63 will appear again. Indeed, the trick the manual suggests doesn’t work at all. 

What I discover going through this problem is- it’s actually a problem with the PC board, not the recirculation circuit. 

In this case, you need to replace the motherboard and it will erase the error code 63. To learn more about this, you can check out the following video:

Noritz Tankless Water Heater Error Code 66

Failure of the bypass flow control valve will cause the water heater to throw the error code 66. 

The bypass flow control valve will not work if there is blockage in that valve or it gets damaged. 

How To Fix: 

To fix this issue, first inspect the bypass flow control valve for restrictions and release the blockage from it if needed. 

If cleaning the bypass flow control valve doesn’t bring any luck, you must replace this valve. 

Noritz Tankless Water Heater Error Code 67

When the Air Gas Mixer (AGM) works intermittently or functions abnormally, your Noritz Water Heater will flash the error code 67. 

Generally, the AGM adjusts the air and gas proportionately for proper combustion. If the AGM gets stuck due to excessive buildup in its housing, the dial on the AGM won’t move to adjust the air and gas. Consequently, the error code 67 will blink on the remote controller display. 

Turns out, loose or damaged wiring of the AGM can be responsible for the error code 67. 

How To Fix: 

First off, check the AGM housing for debris buildup. You should remove the AGM to access its housing. So, unscrew the three nuts that hold the AGM in place. Then, clean the housing of the AGM. 

Then, reset the Air Gas Mixture. In this case, just shut off the electric supply to the unit, wait 30 seconds, and restore the power to the unit. Now, the AGM will try itself to calibrate by rotating its dial with the full range of motion. 

Lastly, inspect the wiring of the AGM. Ensure you plug the harness connector snugly and no wires come loose from the connector. 

Noritz Tankless Water Heater Error Code 71

Gas valve abnormality is what causes the water heater to pop up the error code 71. The gas valve will function abnormally if there is an issue with the circuit board. This problem is common on newer installations when you power up the unit from a backup battery. 

How To Fix: 

I recommend you test the main gas valve and solenoid electrically. A functional gas valve and solenoids should receive between  14-16 volts DC if you have a small unit like the NC1991 when the unit is operating. 

If you don’t receive 14-16 volts DC at the gas valve and solenoids, I bet the circuit board is at fault. In this case, replacing the circuit board will be a simple fix to this issue. 

Noritz Tankless Water Heater Error Code 73

A problem with circuit board setting will be responsible for the fault code 73. Your Noritz Unit throws this error code due to the following reasons: 

• You may change the jumper connection or the dip switch while supplying power to the unit.
• Program the circuit board incorrectly. 

How To Fix: 

For the first problem, I recommend you change both the jumper wires or play with the DIP switch setting after shutting the electric power off to the unit. 

Secondly, program the circuit board following the instructions mentioned in the manual. 

Finally, unplug the unit from the electric connection for 30 seconds. Then, plug the unit again to reset the diagnostic code. 

Noritz Tankless Water Heater Error Code F76

This fault code will appear on this remote controller display if there is a miscommunication between two tankless water heaters. It is a common problem if you connect two units using the Quick-Connect cord. 

The reason behind the issue is to hook up two remotes to control two Quick-Connected water heaters. 

How To Fix: 

When you connect two tankless units, a single remote controller will help you handle both water heaters. So, ensure you hook up only a remote when you connect two units. If this issue still persists, call a certified technician for help. 

Noritz Tankless Water Heater Error Code 90

A fault code 90 indicates improper combustion. Abnormal combustion will occur due to the improper mix of air and fuel. 

The following culprits are responsible for the unit to pop up the error message 90: 

• Unit receives insufficient gas supply
• The exhaust vent gets clogged
• Fan motor gets restricted by dirt and debris
• You don’t set up the DIP switch settings improperly for elevation, pipe size, or length

How To Fix: 

First off, check the gas valve on the unit to make sure you fully open it. Otherwise, gas will not flow to the unit freely. To turn the gas valve on, just move the gas valve counterclockwise. 

Secondly, inspect the exhaust vent and remove blockage from it if needed. 

For a dirty fan motor, you must disassemble the unit to get the fan motor assembly. Fortunately, I already break down the step-by-step procedure of cleaning the fan motor in this article on Noritz Tankless Water Heater Maintenance. 

Lastly, ensure you fine-tune the DIP switch setting according to the manual for elevation, pipe size, and length. 

To learn more about Noritz Code 90, read this article.

Noritz Tankless Water Heater Error Code 91

An error message 91 stands for incorrect gas type. 

If you don’t feed your water heater with the correct type of gas, the unit will pop up the diagnostic code 91. Turns out, setting the gas manifold pressure incorrectly can also be the culprit behind this issue. 

How To Fix:

Ensure you fuel up your water heater with the proper gas type. To check what type of gas your unit requires for proper operation, take a look at the rating plate of the unit. If the unit demands natural gas, feed it with the natural gas. 

Secondly, make sure you adjust the gas manifold pressure according to the manual. Also, don’t forget to check the fan, burner, and heat exchanger periodically and clean them. 

How Do You Reset A Noritz Tankless Water Heater?

It’s very simple to reset a Noritz Tankless Water Heater. 

To reset the water heater, unplug the unit from the electrical outlet. Wait for 30 seconds. Then, plug the unit into the electric outlet, which will reset the unit successfully. 

Note: 

Resetting the unit will bring no luck for you to erase an error code unless you fix the source of the issue. For example, if your tankless unit pops up the error code 11, you must first solve the issues behind this error message.

If you reset the unit without solving the reasons responsible for the error code 11, the code will come again. So, resolve the issues responsible for a specific error code. Then, reset the water heater. 

End-Note

This article is a bible for homeowners who have a Noritz Tankless Water Heater. I considered this guide as a bible because you can find every solution for every error code your unit will pop up. 

So, it’s worth bookmarking this article so that you can find it handy when needed. Just open this bible and follow the directions to erase a specific error code. Happy Plumbing!

Read Also:

• Noritz Tankless Water Heater Troubleshooting