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 thoroughly and do not attempt to relight. Call a professional immediately.
- 1. Decode blink pattern: Refer to the A.O. Smith label or owner's manual to interpret the status light flashes (e.g., 7 flashes for an FV sensor fault).
- 2. Clean air intake: Vacuum and brush the combustion air intake screen located at the base of the heater to restore proper airflow.
- 3. Inspect FV sensor: Locate the flammable vapor sensor near the base of the unit. Ensure it is clean, dry, and properly connected.
- 4. Reset or replace: Some lockout conditions may require replacing the FV sensor and/or the gas control valve. This procedure should only be performed by a qualified technician.
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Repair Difficulty
Hard
4/5
Required Part
Flammable Vapor Sensor
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