Noritz Tankless Error Codes: What They Mean & What to Do
Your Noritz is showing a code. Here’s what the most common ones mean and what to do next.
Updated October 2026 · By the Hot Water Heater Factory team
Noritz error codes and what they mean
| Code | What it means | What to do |
|---|---|---|
| 11 | Ignition failure: the unit isn’t firing | Check that the gas is on (and the propane tank isn’t empty), then text us. |
| 12 | Flame failure or weak flame | Usually a gas or airflow problem. Text us the code. |
| 16 | Outlet water temperature spiked (overheating) | Often scale buildup. The unit may need descaling. |
| 29 | Condensate drainage problem | Check that the condensate drain line isn’t blocked, then text us. |
| 73 | Circuit board setting problem | Unplug the unit for 30 seconds and plug it back in. If the code returns, text us. |
| F76 | Communication error between two connected units | Make sure only one remote is connected. If it continues, text us. |
| 90 | Combustion abnormality (air-fuel mix) | Can be low gas supply, a blocked vent or debris in the fan. A technician needs to check this. Text us the code. |
| No code | No hot water, no code | The unit needs at least about 0.5 gallons per minute of flow to start. Open the hot tap fully, then text us if it still won’t fire. |
Code meanings come from Noritz’s published guidance. Codes can vary by model, so check your owner’s manual too.
What should I do when my Noritz shows a code?
- Write down the code. If it shows more than one, note each one.
- Turn off the hot water taps. Some codes clear when the unit is turned off and back on, but if the code comes back, the unit is telling you something.
- Don’t keep resetting codes for overheating, flame or gas problems.
- Text us the code and a photo of the label. We’ll tell you what it likely means and bring the right parts.
Other brands: Rinnai codes · Navien codes · Takagi codes. Many codes come from scale buildup; see tankless descaling and maintenance.
Questions we hear a lot
What does code 11 mean on a Noritz?
Ignition failure. The unit is missing gas, air or spark to light. Check that the gas is on and the propane tank isn’t empty, then text us.
What does code 90 mean on a Noritz?
A combustion problem from the wrong mix of air and gas, often from low gas supply, a blocked vent or debris in the fan. It needs a technician to check gas pressure and venting.
Why does my Noritz show code 16?
The outlet water got too hot, usually because scale buildup is reducing heat transfer. Descaling often fixes it.
Noritz showing a code? Text us now.
Send a photo of your water heater’s label and tell us what’s happening. A real person texts you back.