Rinnai Water Heater Fault Codes
Every documented Rinnai tankless and tank water heater error code, what it means, and when it needs a professional.
This page covers Rinnai's residential tankless and condensing water heater lineup — RL, RU, RUC, RE, CU, and CX series units and similar models that show a two-character fault code (numbers like 11 or 65, or the letter code LC) on the digital remote control or built-in display. Where Rinnai's diagnostics differ by model series, each code's own page notes which equipment it applies to.
How to read the display
Rinnai tankless units generally show the fault code directly as text or digits on the remote control or LED display — you don't need to count blinks or interpret a flash pattern the way you sometimes do on tank-style water heaters. A code like 11, 12, or 65 appears exactly as written on the readout. LC is the one exception worth knowing about: the display alternates between "LC" and your set temperature along with a beep, because it's a maintenance reminder rather than a fault lockout, and the unit keeps making hot water while it's showing. If you can't find a display or remote on your unit, check the installation manual for your specific model — some wall controllers surface the same codes through an LED indicator instead of a text readout.
All Rinnai codes
| Code | What it means | |
|---|---|---|
| 11 | No Ignition — unit called for heat but didn't light | Full page → |
| 12 | Flame Failure — burner lit, then lost flame | Full page → |
| 10 | Air Supply or Exhaust Blockage | Full page → |
| 14 | Thermal Fuse Tripped (overheat safety device) | Full page → |
| LC | Scale Build-Up Warning (maintenance alert, unit still runs) | Full page → |
| 16 | Over Temperature Warning | Full page → |
| 61 | Combustion Fan Failure | Full page → |
| 25 | Condensate Trap Error (condensing models) | Full page → |
| 65 | Water Flow Control Fault (bath-fill valve) | Full page → |
| 32 | Outgoing Water Temperature Sensor Fault | Full page → |
No code showing — just a symptom?
Sometimes the display isn't visible, or nothing's actually flashing a code yet. Start from what's happening instead:
- No hot water from a tankless water heater
- Water heater ignition failure
- Error code flashing or blinking
- Water not hot enough or runs lukewarm
- Cold water sandwich effect on a tankless unit
Know the code already?
The code lookup searches every code on this site, Rinnai included, by brand and by the code itself.