Furnace shows F6, burner shuts down unexpectedly during operation

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.

Possible Causes

Defective gas valve modulation coil, Loose modulation connector, Faulty control board modulation output

Safety first: Isolate gas and power. Gas valve work must only be done by certified gas technicians.

Visually inspect the gas valve and its electrical connectors.
Ensure the modulation coil connector is firmly seated and free of corrosion.
Restore power and observe operation; if the burner lights but then cuts out as it tries to modulate, the valve or PCB may be at fault.
Further diagnosis (coil resistance, live modulation signal) must be performed by a qualified technician with appropriate equipment.

Professional Required 5/5

ATAG gas valve assembly

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