Low
S.4 on Vaillant ecoMAX System 612

Your boiler is operating normally and is currently in the process of heating your radiators.

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.

What the manual says

Manufacturer manual

Burner ignited (heating operation)

From this model's manual
Verified against the Vaillant Ecomax 613 installation & service manual, page 45.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This is not a fault, but a status message indicating that the boiler has successfully ignited the burner to provide heat to your radiators. It shows the system is responding correctly to a request for heating from your thermostat and is performing its standard internal checks during operation.

This code is most frequently seen during the autumn and winter months when the central heating is active and the boiler is working to maintain the temperature of your home.

DIY fix possible

No action required; this is a status code indicating normal operation.Ensure your thermostat is set to the desired temperature.Check that your radiator valves are open if you require more heat.

Find a Gas Safe engineer
Search the official register →

Avoid the next call-out bill

A cover plan would handle faults like S.4: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

Related guides you might find useful