Which models this covers
Rinnai SENSEI N-Series condensing units (RU199i/RU180i/RU160i/RU130i and the “e” outdoor versions), plus many non-SENSEI models covered by Rinnai’s diagnostic code guide (V-series, RL, RUC, RU80–RU98, RUR98, C199). RX- and RE-series manuals weren’t reviewed. Codes differ between control boards, so check the code chart printed on your unit or in its manual if your model isn’t listed.
How to read the code
The code flashes on the temperature controller or the unit’s display. Write it down, then try the homeowner check below. Turning the unit off and on clears many codes once the cause is fixed.
Error codes
| Code | What it means | What to do |
|---|---|---|
| 10 | Air supply or exhaust blockage, or condensate trap full | Make sure vents outside aren’t blocked, the condensate line isn’t clogged, and (indoor units) the internal air filter is clean. Otherwise, call a pro.Pro |
| 11 | No ignition | Check the gas is turned on at the heater and meter, and your propane tank isn’t empty. Otherwise, call a pro.Pro |
| 12 | No flame (flame failure) | Same checks as code 11: gas on, propane tank not empty. Otherwise, call a pro.Pro |
| 14 | Heat exchanger overheat | Flush (descale) the heat exchanger per the manual and treat hard water. If it returns, call a pro.Pro |
| 16 | High outgoing water temperature (safety shutdown) | Call a pro.Pro |
| 19 | Electrical grounding problem | Call a pro.Pro |
| 25 | Condensate pump (accessory) problem | Make sure the condensate reservoir is empty and the pump runs. Otherwise, call a pro.Pro |
| 32 | Outgoing water temperature sensor (thermistor) fault | Call a pro.Pro |
| 33 | Heat exchanger temperature sensor fault | Call a pro.Pro |
| 52 | Gas valve fault | Call a pro or Rinnai technical support.Pro |
| 61 | Combustion fan fault | Call a pro.Pro |
| 79 | Water leak detected (non-SENSEI models with leak sensor) | Look for water around and under the unit. Shut off the water and call a pro.Pro |
| LC / LC0–LC9 | Scale build-up in the heat exchanger (non-SENSEI models) | Flush the heat exchanger per the owner’s manual. Pressing On/Off 5 times gives a temporary run while you arrange it. |
| SS / 55 | Scale/service reminder (SENSEI models) | Flush the heat exchanger. Reset by pressing On/Off 5 times within 5 seconds. |
Sources
These codes are transcribed from the manufacturer’s own documentation. Many websites repeat codes that don’t match the manuals, so when in doubt, trust the chart on your unit.
- Rinnai N-Series (SENSEI) Installation & Operation Manual 100000467
- Rinnai Tankless Diagnostic Codes guide 100000652 (technician)
Code pointing to a big repair? Check whether to repair or replace before you pay for it.
Frequently asked questions
What does code 11 mean on a Rinnai tankless?
Code 11 means no ignition. Rinnai’s first checks are that the gas is turned on at the heater and the meter, and that a propane tank isn’t empty. If those are fine, a technician should check gas pressure, the igniter and the gas line size.
What does LC mean on a Rinnai water heater?
LC means scale (lime) is building up in the heat exchanger, so it needs flushing with a descaling solution. On newer SENSEI models the same reminder shows as SS or 55. Flushing regularly prevents overheating codes like 14.
What does code 25 mean on a Rinnai?
On Rinnai units, 25 relates to the condensate pump accessory: make sure the condensate reservoir is empty and the pump runs. Some websites say it’s an inlet temperature sensor, but Rinnai’s documentation lists that as a different code.