Meaning
Ignition attempt failed or flame was not detected.
Vaillant fault code
Vaillant F28 Fault Code — Ignition Failure
F28 means the boiler failed to ignite safely. Do not repeatedly reset if the code returns.
Possible causes
Gas supply issue, frozen condensate, ignition electrode fault, flame detection fault or gas valve fault.
Action
Check other gas appliances and external condensate pipe if safe. If unresolved, book a Gas Safe engineer.
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