A.O. Smith Flammable Vapor Ignition Resistance (FVIR) System Lockout

A.O. Smith water heater status light blinking but no hot water (lockout condition on FVIR models)

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Tripped flammable vapor sensor, Blocked combustion air intake screen, Overheated combustion chamber, Faulty FV sensor

How to Fix / Troubleshooting

Safety: If flammable liquids were spilled near the heater, ventilate the area and do not attempt to relight. Call a professional.

  • 1. Decode blink pattern: Refer to the A.O. Smith label to interpret the status light flashes (e.g., 7 flashes for FV sensor fault).
  • 2. Clean air intake: Vacuum and brush the combustion air intake screen at the base of the heater to restore airflow.
  • 3. Inspect FV sensor: Locate the flammable vapor sensor near the base. Ensure it is clean, dry, and properly connected.
  • 4. Reset or replace: Some conditions require replacing the FV sensor and/or gas control valve. This should be done by a qualified technician.
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Repair Difficulty

Hard 4/5

Required Part

Flammable Vapor Sensor
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