Tankless Error-Code Lookup: Rinnai, Navien & Noritz
Type your tankless unit's error code. We list only codes verified from multiple sources — anything else, we say so instead of guessing.
Clarksville, TN · Mon–Fri 7AM–7PM · Sat 8AM–4PM · 24/7 emergency dispatch
Important: code meanings can vary slightly by model and year, and some codes differ between tankless units and boilers from the same brand. Always check your unit's own manual as well. A code names the system that failed; it rarely names the exact part. For gas-related codes, never bypass a safety control, and if you smell gas, leave the house and call your gas utility from outside.
Enter a code above, or browse the full verified table below.
Full verified code table (17 codes)
| Brand | Code | Meaning | First checks / next step |
|---|---|---|---|
| Rinnai | 10 | Air supply or exhaust blockage | Check the vent terminal for obstructions and clearances; do not run the unit on repeated resets if venting is suspect. |
| Rinnai | 11 | No ignition — burner never lit | Check gas supply (valve open, other gas appliances working). If gas is flowing, igniter or flame-sensing diagnosis is needed. |
| Rinnai | 12 | Flame failure — flame lit, then lost or not sensed | Flame sensor, gas pressure, or venting recirculation. Note whether a flame is visible through the view window. |
| Rinnai | 14 | Thermal fuse / overheat protection triggered | Overheat event, often following scale buildup or poor heat transfer. Descaling and heat-exchanger checks are the usual next steps. |
| Rinnai | 16 | Over-temperature warning | Outlet temperature abnormally high. Scale, flow restriction, or sensor fault — do not keep resetting it. |
| Rinnai | LC | Scale buildup in the heat exchanger — flush needed (service reminder) | Descaling is due. In Clarksville water this is the most common tankless service need; ignoring it escalates to lockout. |
| Noritz | 11 | Ignition failure | Gas, air, or spark missing. Check gas supply first, then ignition components. |
| Noritz | 12 | Flame loss during operation | Flame established, then lost — gas pressure, airflow, or flame detection. |
| Noritz | 14 | Thermal fuse failure / overheat protection | Overheat event, frequently following a scaled or dirty heat exchanger. |
| Noritz | 16 | Abnormally high output temperature (overheat) | Temperature spike, commonly from scale restricting flow and heat transfer. |
| Noritz | 61 | Fan motor abnormality | Fan not operating as expected; venting and fan diagnosis needed. |
| Noritz | 90 | Combustion abnormality (incorrect fuel-air mixture) | Gas supply, venting obstruction, or combustion-fan issue. Treat as a prompt service item. |
| Navien | E003 | Ignition failure (tankless models) | Gas supply, igniter, flame rod, or grounding. Check gas valve open and other gas appliances working first. |
| Navien | E012 | Flame loss (tankless models) | Burner lit, then flame dropped out — gas pressure, dirty flame sensor, or partial vent/air-filter blockage. |
| Navien | E016 | Heat-exchanger overheat | Scale buildup, restricted flow, or clogged filters. Descaling is the usual first step. |
| Navien | E030 | Abnormal exhaust temperature | Flue too hot — blocked vent, recirculating exhaust, or scale in the exchanger. Prompt diagnosis. |
| Navien | E110 | Exhaust blockage | Vent terminal blocked or restricted, frozen condensate, or intake restriction. Do not run on repeated resets. |
Codes deliberately omitted: any code we could not corroborate from at least two independent sources with the same meaning, and any code where sources disagreed (for example, Noritz code 29, described as both an air-pressure fault and a condensate-pump fault by different sources). If your unit shows one of those, call us with the brand, model, and exact code and we will confirm it against that model's manual rather than guess.