F28
Saunier Duval Ignition Lockout (No Flame Detected)

Boiler displays F28 and fails to ignite, multiple ignition attempts heard

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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

No gas supply or low pressure, Air in gas line after interruption, Faulty ignition electrode or cable, Gas valve not opening

How to Fix / Troubleshooting

Safety first: Do not repeatedly reset the boiler if you suspect a gas leak. Ventilate the area and avoid naked flames.

User-level checks:

  • Confirm that other gas appliances (hob, oven) are working to rule out a general gas supply issue.
  • Ensure the boiler's gas isolation valve is fully open.
  • If gas supply was recently interrupted, wait a few minutes and try a single reset to clear air from the line.

If F28 persists:

  • A qualified engineer should check ignition electrode condition and spark, gas valve operation, and inlet pressure.

Warning: Do not attempt to dismantle gas components yourself.

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Repair Difficulty

Hard 4/5

Required Part

Ignition Electrode / Gas Valve
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