Nicolette Forbes

By: Nicolette Forbes on May 1st, 2022

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Top Issues With Tankless Water Heaters

Are you in the market for a tankless unit and want to know what problems to expect? Or do you have a tankless water heater and have been experiencing issues with your unit? 

Knowing the issues that could arise with a tankless water heater and knowing when to address them is key to getting the most out of your unit. Tankless water heaters are an investment, and whether you are getting ready to buy one or already have one, we here at Monkey Wrench Plumbing want to make sure you are prepared for anything including when your unit starts flashing error codes as we have been dedicated to providing the best service to our clients since 2007.

In this article, I will walk you through the top issues seen with tankless water heaters and how to fix them. By the end, you’ll have a clear understanding of what these problems mean and when to call us or your local plumber for help. Let’s get started! 


What is an error code? What are the top issues seen with tankless water heaters?

Error codes are numeric or alphanumeric (numbers and letters) codes that appear when a device fails to do something it can. When dealing with any device, you are bound to deal with several problems, and a tankless water heater is no different. Because water heaters are sensitive, they could begin to leak, stop providing hot water for your home, or completely shut down and may need a reboot (which is why it is recommended that you get yearly maintenance performed on your tankless water heater).

An error code logo

The top issues that you typically see are:

  1. Dirty Unit
  2. No Gas
  3. Flame Loss

The error codes usually indicate that your tankless water heater is dirty. However, depending on your unit, it could suggest other problems as well.

1. Dirty Unit 

Like anything else, your tankless water heater gets dirty. Over time, your unit will collect dust and debris that will cause this particular problem to arise. On Noritz models, that will appear as “Error Code 90,” or for Navien models, it’ll pop up as “Error Code e760.” When that happens, you can either clean the unit yourself or call your local plumber or us for maintenance. What does that look like exactly? 

Here at Monkey Wrench, our maintenance for a tankless water heater involves: 

  1. Running vinegar solution through the tankless water heater for about an hour.
  2. Taking the gas manifold off for cleaning.
  3. Take the fan out to clean.
  4. Removal of ignitor for cleaning.
  5. Put the unit back together to adjust gas manifold pressures.

When the unit gets dirty, it will still try to provide hot water for you and will self-adjust your gas pressures. Because of this, the gas manifold will need to be reset to factory settings as part of the maintenance.

2. No Gas

Sometimes the gas will cut out from the unit, and it’s almost always because of the earthquake shutoff valve that was tripped. “How does that happen?” you ask? Well, if your tankless unit’s gas meter is in a high-foot-traffic area, the pipes near the gas line can be bumped into, shutting off the gas line. With Noritz models, an “Error Code 11” will appear, and with Navien models, it would show “Error Code e003.” 

Now, if the earthquake shutoff valve is the reason behind this error code, you can use a flathead screwdriver to reset the valve and allow gas to flow back into the water heater. To save on money, try resetting the water heater yourself first before calling your local plumber or us. If the problem persists, there could be something else going on internally with the unit, such as a faulty gas valve. In those cases, we recommend that you call a certified tankless technician or company. 

3. Flame Loss

Flame loss is another common issue with tankless water heaters.  It generally means that the tankless water heater wasn’t running, and then for some reason, it just cut out.  With Noritz models, "Error Code 12” appears, and with Navien models, “Error Code e012” will pop up. But why does this happen?

Some of the reasons your tankless flame would run out include: 

  1. The unit is picking up moisture.
  2. There’s a gas leak.
  3. Something is blocking the vent.

If this happens, it typically means that the issue is more complicated and will likely need to be addressed by a certified technician. 

It is recommended that if you are experiencing this problem, you should shut off your gas and water to the unit, especially if your tankless water heater is indoors. The gas leak could be dangerous to your health and safety. 

While it is rare, your tankless water heater can catch on fire. If yearly maintenance is not performed on your tankless system and you don’t have proper water treatment, a disruption can happen with your tankless unit, especially if there is an unnoticed gas leak from within or surrounding the unit.


A technician performing maintenance on a tankless water heater


Wrapping Things Up With Error Codes

Any time a tankless water heater is giving an error code, it’s recommended to be checked out by a certified technician. Think of it like a car, when the check engine light comes on, you want a professional to look at it, right? The same applies to a tankless water heater. While fixing a tankless water heater yourself may seem possible, we recommend that you still call us or your local plumber to look at your unit so that a certified technician can do a thorough assessment of your water heater to help prevent future issues.

Now, if you’ve still got some lingering questions like “what causes a tankless water heater to leak?” Or, if you’re looking for more information on the types of maintenance offered for a tankless water heater, read the articles below!

Top Three Reasons Tankless Water Heaters Leak

Two Types of Tankless Water Heater Maintenance

Four DIY Steps To Flushing a Tankless Water Heater

Tankless water heaters are not meant to have error codes. Error codes are there to indicate when something is wrong, and we here at Monkey Wrench Plumbing want to make sure that you are prepared for any of the error codes that may flash on your tankless water heater. 

If you have seen any of these codes appear on your tankless water heater or are experiencing any issues with your water heater, call us at (310) 853-8690 or request an appointment by clicking the 'Book' button below.