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Rinnai Error Code FE: Flammable vapors detected (Tankless)

Updated · by Aurora Star Tech Inc.

Rinnai error code FE on a tankless water heater means: Flammable vapors detected. It is also called Rinnai diagnostic code FE.

Critical severityTankless Water HeaterRH180 hybrid

Homeowner? What Rinnai code FE means for you

Stop and call Your tankless water heater is reporting: Flammable vapors detected. This code is a safety shutdown. Turn the tankless water heater off and call a licensed technician. Do not keep resetting it. If you smell gas, leave the house and call your gas utility or 911 from outside.

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.

Call (647) 657-2977Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rinnai error code FE mean?

The flammable vapor sensor on the RH180 hybrid unit has detected flammable vapors, or the sensor/its circuit is faulty.

Applies to: RH180 (hybrid tank-tankless, Non-SENSEI Series)

Common causes of Rinnai code FE

  • Flammable vapors present near the water heater
  • Loose, damaged or broken flammable vapor sensor wiring
  • Sensor improperly mounted or damaged

A technician checks these and 2 other possible causes on site before replacing any part.

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 FE

RH180

Other Rinnai Tankless codes

CodeMeaning
66Bypass flow servo fault
70PC board fault
71Gas solenoid valve fault (SV0–SV4 on Non-SENSEI)
72Flame rod fault
73Burner thermocouple fault
79Water leakage detected
FFMaintenance performed (history marker)
LCScale build-up in heat exchanger (LC, LC0–LC9, 00)
SECascade diagnostic display (error on secondary unit)
SEtInitial settings not yet confirmed
SSService Soon alert (also listed as 55)

All Rinnai Tankless Water Heater error codes →

Rinnai code FE: homeowner questions

What does Rinnai code FE mean?

Flammable vapors detected. The flammable vapor sensor on the RH180 hybrid unit has detected flammable vapors, or the sensor/its circuit is faulty.

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

No. Code FE is a safety shutdown, so keep the tankless water heater off until a licensed technician has checked it.

Can I reset Rinnai code FE myself?

Do not keep resetting it. Repeated resets can hide a safety problem; a licensed technician needs to find the cause.

Who can fix Rinnai code FE 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

Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.63. 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.

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