Display shows F16, heater may cycle on and off rapidly or fail to modulate correctly.

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

Faulty gas valve modulation coil, Incorrect gas valve wiring, Defective combustion control circuit on PCB, Poor gas supply pressure

Critical safety: Combustion and gas valve issues must be handled by a Gas Safe registered engineer. Do not attempt adjustments.

Check other gas appliances: If all gas appliances are affected, contact your gas supplier.
Visual check only: Confirm the modulation coil connector on the gas valve is secure and undamaged.
Do not adjust gas rate: Never alter gas valve settings without proper equipment and certification.
Call a professional: Persistent F16 requires combustion analysis and gas valve/PCB testing by a qualified technician.

Professional Required 5/5

Gas Valve Modulation Coil

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