Rinnai FF
Rinnai FF code: maintenance performed marker
Short answer
FF is not an error. In a Rinnai tankless heater's diagnostic code history, FF is a placeholder showing that a service provider performed maintenance or service. Technicians enter it after a service visit by pressing the UP, DOWN and ON/OFF buttons at the same time. Codes listed before FF happened before the service.
If you are reading your Rinnai's code history and see FF, there is nothing to fix. It is a bookmark left by a technician.
The meaning and steps below come from Rinnai's own diagnostic code guide for its tankless water heaters.
Rinnai lists FF for both SENSEI and non-SENSEI series.
How FF gets there
After finishing maintenance, such as a flush or a repair, the technician presses the UP, DOWN and ON/OFF buttons on the temperature controller at the same time. That records FF in the history.
Why it is useful
- It separates codes from before the service and after it.
- It helps the next technician see whether a problem returned after a repair.
- It is a simple record that maintenance was done, which is useful for warranty discussions.
How to view the code history
- Turn the heater off with the ON/OFF button.
- Press and hold ON/OFF for about 2 seconds, then press the UP button at the same time.
- The last 9 codes display one after another.
- Repeat the same button sequence to exit, then turn the heater back on.
On some models, a scale warning (LC) appears as 00 in the history.
See every code on our Rinnai error codes page.
Common questions
Do I need to do anything about FF on my Rinnai?
No. FF only marks that service was performed. Look at the codes around it to see what happened before and after.
Was this article helpful?
Sorry about that. What was missing?
Please do not include personal information. Links are not accepted.
Thanks for your feedback. It helps us improve our guides.
Other Rinnai codes
| Code | Meaning |
|---|---|
| 02 | No burner operation during freeze protection |
| 03 | Power interruption during bath fill |
| 05 | Bypass flow control device fault |
| 10 | Air supply, exhaust blockage or condensate trap full |
| 11 | No ignition |
| 12 | Flame failure |
| 14 | Thermal fuse or overheat sensor tripped |
| 15 | Venturi control fault |
| 16 | Outgoing water temperature too high (safety shutdown) |
| 17 | Venturi blockage |
| 19 | Electrical grounding fault |
| 21 | Data transfer error after a control board replacement |
| 25 | Condensate drain clogged or condensate pump error |
| 32 | Outgoing water temperature sensor (thermistor) fault |
| 33 | Heat exchanger temperature sensor (thermistor) fault |
| 34 | Combustion air temperature sensor fault |
| 38 | Exhaust gas temperature sensor fault |
| 41 | Freeze protection sensor fault |
| 51 | Inlet water temperature sensor fault |
| 52 | Gas valve or modulating solenoid valve signal fault |
| 54 | High exhaust gas temperature |
| 57 | Burner overheat switch open |
| 58 | Secondary heat exchanger overheat |
| 61 | Combustion fan motor fault |
| 63 | Recirculation low flow |
| 65 | Water flow control device (servo) fault |
| 70 | Control board (PC board) fault |
| 71 | Gas solenoid valve circuit fault |
| 72 | Flame rod (flame sensing) fault |
| 73 | Burner thermocouple fault |
| 79 | Water leak detected inside the unit |
| LC | Scale buildup in the heat exchanger |
| SS | Service soon (maintenance reminder) |
| FF | Maintenance has been performed (service history marker) |