Low
S.11 on Vaillant ecoTEC pro 30 H combi A VUW GB 306/5-3

Your boiler is simply preparing to provide hot water by starting up its internal fan, which is a normal part of its routine operation.

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

The fan start-up for domestic hot water mode is activated.

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

DIY fix possible

Wait a moment to see if the boiler proceeds to ignite and supply hot water normally.Check if the display returns to normal once you turn off the hot water tap.

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

Avoid the next call-out bill

Monthly cover means no unexpected bills when your boiler breaks down.

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 →S.13View →F.32View →

All 82 fault codes on the ecoTEC pro 30 H combi A VUW GB 306/5-3

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

F.00F.01F.10F.11F.20F.22F.23F.24F.25F.26F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.77F.78F.83F.84F.85S.00S.01S.02S.03S.04S.05S.06S.07S.08S.10S.13S.14S.15S.16S.17S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.39S.40S.41S.42S.46S.53S.54S.57S.58S.61S.62S.63S.76S.88S.92S.93S.96S.97S.98S.99

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on a combi.

Read →

Banging, kettling or whistling noise

Each noise points to a different fault.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →