What does the Vaillant S.3 fault code mean?

Your boiler is currently trying to start the ignition process to provide heating, which is a normal part of the startup sequence and not necessarily a fault unless it remains stuck on this screen.

How much does it cost to fix Vaillant error code S.3?

Typical repair cost for the Vaillant S.3 fault is £0-120 including labour.

Vaillant S.3 Fault Code: What It Means & How to Fix It

Technical description

Ignition sequence (heating operation)

What causes this fault?

This status occurs when the boiler begins the physical process of lighting the burner to heat your radiators. It is a natural part of the start-up cycle where the system checks components and prepares the spark to ignite the gas. If the boiler stays on this code without moving forward, it usually means the system is struggling to successfully establish or detect a flame.

DIY fix possible

Check if the display changes to a different code after a few secondsMonitor for any lockout codes if the boiler fails to fireEnsure the gas supply is turned on at the meterPress the reset button if the boiler becomes stuck

Find a Gas Safe engineer

Search the official register →

Related fault codes

S.1View →S.2View →S.4View →F.28View →F.29View →

Your boiler is currently trying to start the ignition process to provide heating, which is a normal part of the startup sequence and not necessarily a fault unless it remains stuck on this screen.

Technical description

What causes this fault?

DIY fix possible

Related fault codes

Related guides you might find useful

Boiler keeps cutting out

Pilot light keeps going out

Is boiler cover worth it?

Recently viewed