Tankless Water Heater Error Codes: What Rinnai Code 11 and 12, Navien E003 and Noritz 11 Mean
Rinnai code 11 means no ignition and code 12 a lost flame. What Rinnai, Navien and Noritz codes mean, safe checks and when to call a plumber.
Rinnai code 11 means your tankless water heater tried to light and never sensed a flame; code 12 means it lit, then lost the flame. Navien’s E003 and E012 and Noritz’s 11 and 12 mean the same things, and the first suspects are a closed gas valve, an empty propane tank, low gas pressure, a blocked vent or a wrong altitude setting. Fort Collins Water Heater Pros repairs tankless units in Fort Collins, Loveland and across Larimer County; here is what each code means and what is safe to check.
Call (970) 305-5633 if a tankless code keeps coming back and we’ll track down the cause.
Call nowTankless error codes at a glance
These meanings come from each manufacturer’s own manuals and support pages. Codes vary by brand and series, so check the model number on your heater’s rating plate.
| Code | Brand | What the manufacturer says it means | First thing to check |
|---|---|---|---|
| 11 | Rinnai | No ignition | Gas valves open, propane in the tank |
| 12 | Rinnai | Flame failure | Gas supply, exhaust terminal clear |
| E003 | Navien | Ignition failure | Main gas supply valve open |
| E012 | Navien | Flame loss | Air intake filter clean |
| 11, 12 | Noritz | Ignition failure, flame loss | Gas supply, then call |
| 111, 121 | Takagi | Ignition failure, loss of flame | Gas supply |
| 10, E110, 90 | Rinnai, Navien, Noritz | Air supply or exhaust problem | Vent terminals clear |
| 14, 16 | Rinnai, Noritz | Overheat shutdown | Call us |
| E016, E030 | Navien | Heat exchanger or exhaust overheating | Off 30 minutes, then call |
| LC, E760 | Rinnai, Navien | Scale buildup or service due | Book a flush |
| 79 | Rinnai | Water leak detected | Shut off the water |
What Rinnai code 11 and code 12 mean
Rinnai error code 11 (No Ignition) means the heater tried to light but never proved a flame; code 12 (Flame Failure) means a flame was detected and then lost. Rinnai’s troubleshooting manual starts both with the gas: every gas valve open, gas in the propane tank, and inlet pressure at or above the minimum on the rating plate at full fire.
Past that, the causes are technician work: air in a new gas line, the wrong gas type selected, a loose or carbon-coated flame rod or igniter, an undersized gas line, meter or regulator, vent problems that let exhaust recirculate into the intake, the altitude setting and moisture in the wiring. Rinnai adds that a code 12 appearing the instant water flows, with no flame visible, points to an electrical short. Its controllers store the last nine codes, so the history survives a reset.
Navien E003 and E012
Navien’s NPE operation manual lists E003 as ignition failure, with checking that the main gas supply valve is open as the first remedy. E012 is flame loss; Navien says to clean the air intake filter and make sure the power cord is properly grounded.
The same manual says a lint-clogged air intake filter shuts the heater down with error 110 and recommends cleaning it every 3 to 4 months. NPE models reset with the Reset button; NPE-2 models use the Back button and list the 10 most recent errors.
Noritz error code 11 and 12, plus Takagi 111 and 121
Noritz defines error code 11 as an ignition failure: the heater senses a demand for hot water but can’t light because air, gas or spark is missing. Code 12 is a flame loss, a weak flame that lights and then goes out.
The Noritz support center lists the gas meter, regulator, gas line and shutoff valves as gas-side causes and says gas troubleshooting belongs to a professional. For code 12 it also flags direct-vent units whose air intake pulls in exhaust. Takagi uses 111 for ignition failure and 121 for loss of flame, and checks the gas supply and inlet pressure first.
Safe checks before you call
If your tankless water heater is not heating and shows a code, write down the code and the model number. Then go in order, and stop at anything your owner’s manual doesn’t cover.
- Smell gas? Stop. Leave without touching light switches and call your gas utility from outside.
- Check the gas. Make sure the valve on the heater’s gas line is open and the stove or furnace still works. On propane, read the tank gauge; Rinnai and Noritz both list an empty tank as a cause.
- Check the power. Look for a tripped breaker or GFCI outlet. Keep the heater plugged in all winter, because Navien’s freeze protection only works while it has power.
- Clear the vent terminals. Look outside for snow, ice, leaves or a nest. Larimer County requires terminals at least 12 inches above the expected snow level, but drifts can still bury one; brush snow away by hand.
- Reset once, as your manual says. Navien uses the Reset button, Noritz resets its code 16 by unplugging the heater for 20 seconds, and Takagi’s ignition codes clear when water flow stops on a single unit. If the code returns, stop.
- Clean the filters your manual covers. Navien’s manual shows owners how to clean the cold water inlet filter (power, gas and water off, unit drained) and the air intake filter.
Vent, air and condensate codes
Rinnai code 10 (air supply or exhaust blockage, or a full condensate trap on SENSEI models), Navien E110 (abnormal air pressure) and Noritz 90 point to combustion air or exhaust. Noritz ties 90, a fuel and air mix that’s off, to low gas pressure, venting faults or dip switches set wrong for elevation or vent length on new installs, and to a dirty unit on older ones.
Winter adds frozen condensate lines: Rinnai says one sets code 10 on SENSEI models, Noritz says it sets code 29, and Rinnai’s code 25 covers a stopped condensate pump or blocked drain. A blocked vent is also a carbon monoxide risk, so if a CO alarm sounds, get everyone outside and call 911 or your gas utility.
Overheat and scale codes
Overheat codes are safety shutdowns. Rinnai’s code 14 (thermal fuse or overheat sensor) signals real overheating, and on non-SENSEI models a one-time thermal fuse may need replacing. Its code 16 is a shutdown after outlet water passed 203°F. For Navien’s E016 (heat exchanger overheating) and E030 (exhaust above 149°F), Navien says to turn the system off for at least 30 minutes, clean the inlet filter and flush the heat exchanger.
Noritz’s code 14 is a significant overheat that breaks a one-time thermal fuse, most often because of scale; Noritz recommends replacing the heat exchanger with the fuse and warns never to bypass it. Its code 16, an outlet temperature spike, also often traces to scale.
Scale has its own codes. Rinnai’s LC (00 in the code history) means a flush is due; a temporary reset, five presses of the controller’s power button, buys about 70 hours before the heater locks out again. Rinnai’s SS is a timed service reminder, and Navien NPE models show E760. Rinnai says hard water must be treated, and our guide on how to descale a tankless water heater covers the flush.
Altitude settings: why Estes Park and Livermore need a check
Each of these brands has an altitude setting, and a wrong one can cause combustion codes. The fuel gas code requires gas input to be adjusted above 2,000 feet, and every town we serve is above 4,600 feet.
- Rinnai: V-series DIP switches set bands of 0-2,000, 2,001-5,200, 5,201-7,700 and 7,701-10,200 feet, and Rinnai warns wrong settings can cause unsafe operation, damage and a void warranty. SENSEI models break at 5,400 feet instead, and altitude is on Rinnai’s checklist for codes 10, 11 and 14.
- Navien NPE-2: the menu offers 0-2,000, 2,000-5,400, 5,400-7,700 and 7,700-10,100 feet, with 0-2,000 as the factory default. Natural gas units at 5,400 feet or higher also need the high-altitude kit, a gas orifice shipped inside the case.
- Noritz and Takagi: Noritz lists elevation dip switches among the causes of code 90. Takagi’s CT-199 bands change at 2,000, 3,000, 5,000 and 7,500 feet, and altitude is on its checklist for code 991.
Fort Collins (5,004 feet at its USGS reference point) and Loveland (4,986) fall in Rinnai’s 2,001-5,200 foot band, though Fort Collins sits right on Takagi’s 5,000-foot line. Livermore (5,890) and Estes Park (7,530) are in the 5,201-7,700 foot band and above Navien’s kit threshold, and Estes Park is close to 7,700. The setting follows the home’s own elevation, so foothill lots need a site check.
When to call a plumber
Rinnai’s troubleshooting manual is written for trained professionals and relies on live gas and electrical tests, so call us for:
- Ignition or flame codes that return after one reset (Rinnai 11 or 12, Navien E003 or E012, Noritz 11 or 12).
- Any overheat code, or any fix involving gas pressure, the flame rod, igniter or wiring.
- Leak codes such as Rinnai 79; shut off the heater’s water supply first.
- Scale codes (LC, SS, E760), before scale becomes an overheat.
Our tankless water heater repair service covers diagnosis, descaling, parts and altitude setup. Licensed plumbers covered by liability insurance do the work, with a written, itemized quote before it starts. If an older unit isn’t worth fixing, we’ll say so; our guide to tankless water heater pros and cons and our page on water heater replacement in Fort Collins help you compare options.
Tankless error code FAQ
What does Rinnai code 11 mean?
No ignition: the heater tried to light but never sensed a flame. Rinnai’s first checks are open gas valves, gas in a propane tank and inlet gas pressure that meets the rating plate.
What is the difference between Rinnai code 11 and code 12?
Code 11 means the burner never lit. Code 12 means it lit and then lost the flame, which Rinnai ties to the gas supply, venting or the flame rod, or to an electrical short if it appears instantly.
How do I fix Navien error code E003?
Navien says to make sure the main gas supply valve is open, then press Reset. If E003 returns, the problem is likely gas pressure, ignition or flame sensing, which needs a plumber.
What does Noritz error code 11 mean?
An ignition failure: the heater sees a call for hot water but can’t light because air, gas or spark is missing. Noritz advises leaving gas-side troubleshooting to a professional.
Can altitude cause tankless error codes?
Yes. Rinnai, Noritz and Takagi list the altitude setting among the checks for ignition or combustion codes, and Navien natural gas units need a high-altitude kit at 5,400 feet or higher, as in Estes Park and Livermore.
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