Rinnai tankless water heater code 11 means No Ignition: the unit called for a flame and never got one. Check two things first, that every gas valve is open and that a propane tank is not empty. After those, Rinnai's diagnostic code manual moves to work for a qualified gas technician.
Figures checked September 2026. Code meanings come from the Rinnai documents under Sources, with page numbers.
| Possible cause, in the order Rinnai checks it | How it is checked | Who does it |
|---|---|---|
| Gas valve closed at the heater, meter or tank | Look at the manual gas valve and the propane gauge | Homeowner |
| Propane tank empty or too small for the load | Tank gauge, then a sizing check | Homeowner, then pro |
| Air left in the gas line after installation | Purge the line | Pro |
| Inlet gas pressure too low | Manometer at the test port | Pro |
| Wrong gas type or gas-type setting | Rating plate, Parameter 10 (A natural gas, B propane) | Pro |
| Igniter not sparking | Spark test, voltage at the PC board | Pro |
| Dirty or loose flame rod or electrode | Remove, clean, new gasket | Pro |
| Venting faults causing exhaust recirculation | Joints, clearances, vent length, materials | Pro |
| Gas valve or PC board failure | Resistance and voltage tests | Pro |
The order follows Rinnai's steps; Rinnai publishes no failure frequencies. Source: Rinnai, Troubleshooting Tankless Water Heater Diagnostic Codes, April 2019.
Code 11 is Rinnai's No Ignition fault. The heater saw water flow and tried to light, but the flame rod never confirmed a flame. Causes split three ways: no gas or too little gas reaching the burner, no usable spark, or a flame the control board cannot detect because the flame rod is dirty, loose or badly wired.
The third group surprises owners. If a flame is visible through the view glass and the unit still faults, Rinnai's step 9 points to the flame rectification circuit or gas system: deposits on the flame rod, a bad connection, the PC board, the gas valve or low inlet pressure, per Rinnai's diagnostic manual, page 14.
On Non-SENSEI units, page 16 adds that a flame rod loose in its bracket, which Rinnai calls a floating flame rod, results in code 11.
Code 11 appears in both model groups covered by Rinnai's diagnostic manual, SENSEI and Non-SENSEI, and each group has its own checklist. SENSEI steps are on pages 14 and 15 of document 100000652. Non-SENSEI steps are on pages 16 and 17.
| Group in Rinnai's manual | Example models | Code 11 steps |
|---|---|---|
| SENSEI Residential | RU199i, RU180i, RU160i, RU130i and the "e" outdoor versions | Pages 14 to 15 |
| SENSEI Residential with Pump | RUR199i, RUR160i, RUR199e, RUR160e | Pages 14 to 15 |
| SENSEI Commercial | CU199i, CU160i, CU199e, CU160e | Pages 14 to 15 |
| Non-SENSEI Value and Luxury VC | V65i, V75i, V94i, RL75i, RL94i, RLX94i | Pages 16 to 17 |
| Non-SENSEI KCM, KBD, KB, KBP | RUCS75i, RUS75e, RUC98i, RU80i, RU98e, RUR98i | Pages 16 to 17 |
The model list is on page 2 of Rinnai's April 2019 troubleshooting manual. It predates the SENSEI RX series, and the SENSEI RX manual (revision 03, March 2025) prints no code table, pointing owners on page 58 to the Tech Data Sheet inside the front cover.
Fix code 11 by confirming the gas supply first, because that is the only part of Rinnai's list an owner can safely check. Both of Rinnai's code 11 lists open with the same two items: every gas valve open, and gas in the propane tank. If both are fine and the code returns, stop and book a technician.
Owner checks:
Technician steps, pages 14 and 15 (SENSEI):
Rinnai's figures for that work: 11 to 13 VDC at the spark electrode during ignition, a 0.138 in. (3.5 mm) electrode gap, 18 to 22 ohms across the gas valve solenoid, and inlet pressure never above 10 inches water column on natural gas or 13.5 inches on propane, per Rinnai document 100000652, pages 14 and 15. The gas valve direction and the snow-and-debris vent check come from pages 55 and 64 of the SENSEI RX manual.
Clearing the display does not repair code 11. The SENSEI RX manual gives one clearing method, in its condensate pump test on page 41: press On/Off, wait five seconds, then restore power. Rinnai gives no separate reset for code 11, and every step on its code 11 list deals with a physical cause.
A reset also adds little on newer units. Rinnai Technical Bulletin 166, dated December 2019, raised the number of ignition attempts on SENSEI heaters from three to 18 before the display shows code 11. The aim was to purge residual air from the gas line, so the board has already retried many times before the code shows.
To see the history, the RX manual's page 58 method is: switch the heater off, hold On/Off for two seconds, then press the up arrow at the same time. The last nine codes flash in turn. Repeat the same press to exit, per the SENSEI RX manual, March 2025. Repeated 11s suggest a recurring fault, not a one-off gas interruption.
Yes, once the gas valve and tank checks come up clean. Rinnai's diagnostic manual states that only trained and qualified professionals may follow its instructions, and the SENSEI RX manual says repairs and maintenance shall be performed by a trained and qualified professional. The remaining steps involve live gas and energized wiring.
Safety: stop and call a licensed gas professional if any of these apply. You smell gas: Rinnai's instructions are not to light any appliance, not to touch electrical switches or use a phone in the building, to call the gas supplier from a neighbor's phone, and to call the fire department if the supplier cannot be reached. Any part of the heater has been under water: Rinnai says not to use it. The code returns after you confirmed gas is on. Never adjust the internal gas valve; Rinnai says doing so voids the warranty. Sources: Rinnai document 100000652, page 3 and SENSEI RX manual, pages 54 and 64.
Gas-side repairs in general are covered in the gas hot water heater repair guide.
A code 11 repair is usually a service call plus, at most, a small part. HomeAdvisor's tankless repair guide, updated June 19, 2026, puts the national average at $600 within a $75 to $1,300 range, and technicians at $45 to $200 an hour. The part prices below were checked on September 16, 2026.
| Item | Price | Source and date |
|---|---|---|
| Electrode/flame rod assembly 105000232 (listed for RU, RUR, CU and RSC models) | $44.47 | TanklessParts.com, checked Sep 16, 2026 |
| Same part, 105000232 | $78.88, shown unavailable | Midwest Appliance Parts, checked Sep 16, 2026 |
| Igniter 105000180 for RL75 and RL94 | $61.41 | Blackhawk Supply, checked Sep 16, 2026 |
| Tankless gas valve replacement | About $350 on average | HomeAdvisor, June 2026 |
| Tankless vent repair | $50 to $125 | HomeAdvisor, June 2026 |
| Technician labor | $45 to $200 per hour | HomeAdvisor, June 2026 |
| Tankless repair, typical range | $100 to $650, average $375 | Fixr, January 2025 |
Sources for the table: HomeAdvisor, June 2026, Fixr, January 2025, TanklessParts.com, Midwest Appliance Parts and Blackhawk Supply, prices as listed September 16, 2026. Neither cost guide prices a flame rod job or a PC board on its own line, so no installed figure is given for those. More part-by-part figures are in the water heater repair prices guide.
Only when a defective part caused the code. Rinnai's SENSEI limited warranty, dated October 2024, covers other parts for 5 years and reasonable labor for 5 years on residential units registered within 90 days. It excludes failures from improper installation, including improper venting, incorrect gas type and incorrect gas or water pressure.
| Code 11 cause | Where it falls in the warranty |
|---|---|
| Igniter, flame rod or gas valve failed from a defect | Covered within the parts term; genuine Rinnai parts, fitted by a qualified professional |
| Wrong gas type | Excluded as improper installation |
| Low or incorrect gas pressure | Excluded as improper installation |
| Venting fault or recirculation | Excluded: improper venting (installation) or vent blockage (maintenance) |
| Water or flood damage | Excluded |
| Internal gas valve adjusted | Warranty void, per the diagnostic manual |
The warranty's residential terms are 15 years or 12,000 operating hours on the heat exchanger, 5 years on other parts, and labor that defaults to 1 year without registration, per Rinnai's limited warranty, document 100000655(04), October 2024. That document lists the RX, RXP, RU, RUR and RSC models only, so owners of older series need their own paperwork. Registration and claims are covered in the Rinnai water heater repair and warranty guide.
Repair is the normal answer for code 11. Rinnai's code 11 list ends at the igniter, flame rod, gas valve and PC board, not the whole heater. The exception is step 16 on page 15: liquid from the condensate drain while the heater is off is a common sign of a leaking heat exchanger.
| Situation | Lean | Basis |
|---|---|---|
| Flame rod or igniter replaced inside the parts term | Repair | Parts covered under the October 2024 warranty |
| Gas valve or PC board failed after the parts term | Get a written quote, then compare with a replacement price | HomeAdvisor gas valve average, June 2026 |
| Code 11 plus liquid from the condensate drain while idle | Have the heat exchanger checked before paying for ignition parts | Rinnai 100000652, page 15 |
| Heater has been under water | Stop using it and call a technician | Rinnai 100000652, page 3 |
To compare a gas valve quote of about $350, the HomeAdvisor average from June 2026, with a new unit, use the model prices in the Rinnai tankless water heater cost guide. If the display shows 12 instead, see Rinnai code 12 flame failure; other codes are in Rinnai tankless error codes explained.
No. Rinnai's code 11 list checks the gas supply, gas pressure, gas type and venting before it reaches the igniter, and a dirty or loose flame rod produces the same code with a working spark. Replace the igniter only after a spark test fails.
Yes. Rinnai's list includes air left in the gas lines after installation, and Technical Bulletin 166 raised SENSEI ignition attempts to 18 specifically to help purge residual air from the gas line, per Rinnai, December 2019.
Code 110 is the I-Series boiler equivalent of code 11. Rinnai's Technical Bulletin 166, dated December 2019, applies the same ignition-attempt change to SENSEI water heaters showing code 11 and I-Series boilers showing code 110.
The code means the heater stopped trying to light. If you also smell gas, leave and call the gas supplier from outside the building, as Rinnai's manuals instruct.
Independent Research
Published ranges for tank, tankless and heat pump replacement, the failures that justify a repair, and the ones that do not. Sourced, dated, and free to read.
