What Causes Noritz Error Code 90 and What the Possible Solutions

Don’t be alarmed when you see Noritz error code 90 flashed on your remote control’s screen. Error codes 90, 91, or 99 are basically the same: they show you that your unit is struggling with a combustion issue. Although the issue may seem serious, it’s not overly serious or risky, but you shouldn’t do anything dangerous with the unit.

If you have doubts about performing the check on your own (especially if you completely have no idea what to do with your unit), you should ask for help from a professional. NEVER try to tweak the unit on your own.

Noritz Error Code 90

Your Manual and Error Code Meaning

You can see the error code because all Noritz units are connected to a remote control with an LCD screen. When the unit is running well, you won’t see anything. But when there is an issue, then you will see the code.

Noritz Tankless Error Code 90

If you consult the Noritz tankless water heater manual, some error codes are listed there. These are the most common error codes that may happen to the unit. Be advised, though, that you may not find some of the error codes in your manual. No need to worry; you can always check online. You can even find the Noritz error code list through online research.

In general, the error code 90 is related to combustion. You can check for improper gas-burning or airflow obstruction. Then you can confirm the correct gas pressure and the proper fuel/air mixture. If you have fixed it, you can reset the heater.

Noritz Tankless Water Heater Error Code 90

As it was mentioned before, error code 90 is about general combustion abnormality. However, some people have contacted Noritz tech support and discovered that code 90 can also be about airflow or exhaust error.

Read also: LG Washing Machine Error Code DE

Here are detailed steps to troubleshoot and resolve the issue:

  1. Check the Gas Pressure: Each unit has a minimum flow rate for incoming gas. Insufficient gas can cause restrictions. Ensure the inlet pressure doesn’t drop below the required levels during maximum operation.
  2. Check the Airflow: Ventilation problems, often due to dust, lint, or debris build-up, can cause the unit to overheat. Cleaning intake slots and holes with a portable vacuum or seeking professional help for deeper cleaning might be necessary.
  3. Check the Exhaust: Issues here might be due to obstructed exhaust ducting, incorrect duct size, or a stuck flapper valve.

First-Hand Knowledge and Expert Recommendations

I have firsthand experience dealing with Noritz error code 90 in various situations. Here’s a comprehensive table summarizing key points from multiple sources:

IssuePossible CausesSolutions
Combustion ProblemsInsufficient gas pressure, dirty burner, obstructed manifoldClean intake slots use vacuum, professional cleaning
Airflow IssuesDust, lint, debris in intakeClean intake slots, use vacuum, professional cleaning
Exhaust ProblemsBlocked exhaust ducting, incorrect duct size, stuck flapper valveCheck and clear exhaust duct, ensure correct duct size, inspect flapper valve

Example of Troubleshooting

A user reported that their newly installed tankless unit showed error code 90. The issue was traced back to insufficient gas pressure and incorrect venting installation. The error was resolved after adjusting the gas pressure and correcting the venting setup, demonstrating the importance of proper installation and maintenance.

How to Reset Noritz Tankless Water Heater

Resetting the unit is a complete no-brainer. But it would help if you did it as your last resort if the previous methods don’t work well. You only need to find the Reset button and press it.

You can find it on the front panel. If you have done the reset solution and the issue still isn’t resolved completely, then you should call a licensed professional or an authorized technician.

Those are the facts related to the code error, including the possible reasons and the possible solutions. At least, now you won’t be panicky anymore when you get Noritz error code 90 on your remote.

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John Burns is an experienced author and expert home improvement advice. With years of practical experience in the field authored several informative articles on various aspects related to home improvement, including installation, maintenance, and repair.