Rinnai Error Code FF: Maintenance performed (history marker) (Tankless)

Updated October 13, 2026 · by Aurora Star Tech Inc.

Rinnai error code FF on a tankless water heater means: Maintenance performed (history marker). It is also called Rinnai diagnostic code FF.

Low severityTankless Water HeaterNon-SENSEI · RH180 hybrid · SENSEI RX/CX · SENSEI

Homeowner? What Rinnai code FF means for you

Usually minor Your tankless water heater is reporting: Maintenance performed (history marker). This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.

Safe things you can check yourself

Check that gas reaches the house: other gas appliances work, or the propane tank is not empty.
Make sure the heater is plugged in and its breaker is on. In winter, keep the power on: it protects the unit from freezing.
Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
Check that the hot and cold water valves under the heater are fully open.
If you have a remote controller, turn it off and on once. If the code comes back, call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rinnai error code FF mean?

Not a fault: a marker in the diagnostic code history showing that a service provider performed maintenance or service on the unit.

Applies to: SENSEI Series, SENSEI RX/CX Series, Non-SENSEI Series

Common causes of Rinnai code FF

Service provider logged a maintenance entry after servicing
Marker entered manually on the controller

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Rinnai models that use code FF

Show all 89 models

C199e C199i CU160e CU160i CU199e CU199i CX160i CX199i CXP160i CXP199i R50LSi R63LSe2 R75LSe R75LSi R94LSe R94LSi R98LSe R98LSe-ASME R98LSi R98LSi-ASME RC80e RC80i RC98e RC98i RE140e RE140i RE160e RE160i RE180e RE180i RE199e RE199i REP160e REP160i REP199e REP199i RH180 RL75e RL75e(A)RL75i RL75i(A)RL94e RL94i RLX94i RSC160e RSC160i RSC199e RSC199i RU80e RU80i RU90e RU98e RU98i RU130e RU130i RU160e RU160i RU180e RU180i RU199e RU199i RUC80i RUC90i RUC98i RUCS65i RUCS75i RUR98e RUR98i RUR160e RUR160i RUR199e RUR199i RUS65e RUS75e RX130i RX160i RX180i RX199i RXP160i RXP199i V53De V53e V65e V65i V75e V75i V94e V94i V94Xi

Other Rinnai Tankless codes

Code	Meaning
70	PC board fault
71	Gas solenoid valve fault (SV0–SV4 on Non-SENSEI)
72	Flame rod fault
73	Burner thermocouple fault
79	Water leakage detected
FE	Flammable vapors detected
LC	Scale build-up in heat exchanger (LC, LC0–LC9, 00)
SE	Cascade diagnostic display (error on secondary unit)
SEt	Initial settings not yet confirmed
SS	Service Soon alert (also listed as 55)

All Rinnai Tankless Water Heater error codes →

Rinnai code FF: homeowner questions

What does Rinnai code FF mean?

Maintenance performed (history marker). Not a fault: a marker in the diagnostic code history showing that a service provider performed maintenance or service on the unit.

Is it safe to keep using my tankless water heater with code FF?

Usually yes. Code FF is normally minor, but if it keeps coming back have it checked.

Can I reset Rinnai code FF myself?

You can try one reset (power off for 30 seconds, then on). If Rinnai code FF comes back, the cause is still there and a licensed technician should check it.

Who can fix Rinnai code FF near me?

Aurora Star Tech Inc. repairs Rinnai tankless water heaters in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Tankless Water Heater No Hot Water: What to Check

Troubleshooting guides

No hot water All brands · Tankless Water Heater
Water temperature fluctuates All brands · Tankless Water Heater

Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.64. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.