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 room thermostat is calling for heatMonitor the display to see if it progresses to S.4 (Burner ignited)If the boiler is stuck on S.3 for a long period, try a ResetEnsure the gas supply is turned on at the meter

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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

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