Home/Boiler Fault Codes/Vaillant F28
VAILLANT FAULT CODE
Vaillant F28
The boiler attempted to ignite but failed, and has locked out as a safety measure. Common causes include a blocked burner, a failed ignition electrode, or a gas supply issue — in cold weather it can also follow a frozen condensate pipe.
WHAT F28 TYPICALLY INDICATES
The boiler attempted to ignite but failed, and has locked out as a safety measure. Common causes include a blocked burner, a failed ignition electrode, or a gas supply issue — in cold weather it can also follow a frozen condensate pipe.
WHAT TO DO
Confirm the gas supply is on. If you can see the external condensate pipe and it looks frozen, gently warming it with a warm damp cloth (never boiling water, never opening the casing) is a documented homeowner step. If that doesn't resolve it, This is not a DIY fix — it requires a Gas Safe registered engineer to diagnose and repair safely.
A NOTE ON GAS SAFE REGISTRATION
Any work on the gas side of a boiler in the UK legally requires a Gas Safe registered engineer, it isn't optional. Our engineers are fully Gas Safe registered, and you're always welcome to ask to see ID on the day. This page is general information about what a fault code typically indicates; it is not a substitute for an engineer diagnosing your specific boiler.
Seeing Vaillant F28 on your boiler?
Tell us the code and your postcode. A fully Gas Safe registered engineer will diagnose the actual cause before quoting a fix.
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