Low
S.11 on Vaillant ecoMAX System 612

Your boiler is currently working as it should to heat up your hot water tank.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Pump and fan running (hot water operation)

From this model's manual
Verified against the Vaillant/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 actually not a fault, but a status code informing you that the boiler is currently busy heating your hot water cylinder. It occurs when the system's sensors detect that the water in your tank has cooled down and the boiler has fired up specifically to replenish that heat.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like S.11: 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

S.10View →

All 88 fault codes on the ecoMAX System 612

Seeing a different code? Every code this model can display, in one place.

d.0d.1d.2d.5d.7d.8d.10d.11d.13d.14d.16d.22d.23d.24d.25d.34d.35d.40d.41d.44d.46d.47d.60d.61d.67d.68d.69d.71d.72d.73d.80d.81d.82d.83F.0F.1F.10F.11F.13F.20F.22F.23F.24F.25F.27F.28F.29F.32F.60F.61F.62F.63F.64F.65F.67P.1P.2P.5S.0S.1S.2S.3S.4S.5S.6S.7S.8S.10S.13S.14S.16S.17S.20S.21S.23S.24S.26S.27S.28S.30S.32S.34S.36S.37S.39S.53S.54

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →