What does error code FE mean on a Rinnai tankless water heater?

Flammable vapors detected. The flammable vapor sensor detected flammable vapors.

When should I call a technician for code FE?

Rinnai says leave until safety personnel confirm the area is safe and vapors are removed. Sensor checks are for qualified gas technicians. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Rinnai Tankless Water Heater Error Code FE: Flammable vapors detected

What FE means

The flammable vapor sensor detected flammable vapors.

Likely causes

Gasoline, paint thinner, solvents or other vapors near the heater

Safe first checks

Leave the room. Don't operate switches or the heater.

When to stop

Rinnai says leave until safety personnel confirm the area is safe and vapors are removed. Sensor checks are for qualified gas technicians.

Checked against: Rinnai: Troubleshooting Tankless Water Heater Diagnostic Codes (100000652). Codes can differ by model and year, so confirm with your owner's manual.