Low Information
S.13 on Vaillant ecoMAX 635

Your boiler is currently going through the normal steps to start the ignition process for your hot water.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

Ignition sequence (hot water operation)

What causes this fault?

This code appears when the boiler begins its internal sequence to heat the water for your taps or cylinder. It is triggered by the system's sensors detecting a demand for hot water, signaling the fan to start and the gas valve to prepare for ignition. This is a standard part of the boiler's operation and does not indicate a breakdown.

DIY fix possible

No action required; this is a normal status code, not a faultWait a few moments for the boiler to complete its start-up sequenceMonitor the display to ensures it transitions to a run code

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