Tankless Water Heater Error Codes
Your tankless is showing a code. Pick your brand to see what it means, or text us the code and we’ll tell you.
Rinnai error codes
What each Rinnai code means and what to do.
See Rinnai codes →Navien error codes
What each Navien code means and what to do.
See Navien codes →Noritz error codes
What each Noritz code means and what to do.
See Noritz codes →Takagi error codes
What each Takagi code means and what to do.
See Takagi codes →Updated October 2026 · By the Hot Water Heater Factory team
Common codes by brand
| Problem | Rinnai | Navien | Noritz | Takagi |
|---|---|---|---|---|
| Won’t light (ignition failure) | 11 | E003 | 11 | 111 |
| Flame goes out | 12 | E012 | 12 | 121 |
| Overheating | 14, 16 | E016 | 16 | – |
| Vent or air blockage | 10 | E110 | 90 | 101, 991 |
| Scale buildup | LC | – | 16 | – |
| Fan problem | 61 | E109 | – | 611 |
Many codes are prevented with yearly tankless descaling and maintenance. More on tankless repair and common tankless problems.
Questions we hear a lot
Why is my tankless water heater showing an error code?
The unit found a problem and shut down or warned you to protect itself. The most common causes are the gas supply, a blocked vent, scale buildup and low water flow.
Is it safe to reset a tankless error code?
Turning the unit off and on clears some codes. If the same code comes back, or it’s an overheating, flame or gas code, have it checked instead of resetting it again.
Do you repair all tankless brands?
Yes, including Rinnai, Navien, Noritz, Takagi, Bosch and A.O. Smith.
Tankless 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.