Saunier Duval Ignition Sequence Interruption

Boiler fan runs but there is no ignition and no error code displayed

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 air pressure switch not confirming airflow, Loose connection to gas valve, PCB not sending ignition command, Blocked flue or air intake

Safety first: Turn off power and gas before removing the boiler cover.

Steps to check:

Check the flue terminal outside for obstructions.
Inspect the air pressure switch tubes for kinks or water and refit securely.
Check the electrical connectors to the air pressure switch and gas valve.
Attempt a reset. If the fan runs continuously without ignition, a professional should test the air pressure switch and PCB outputs.

Warning: Do not bypass safety switches to force ignition.

Hard 4/5

Air Pressure Switch / Gas Valve

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