Low
S. 5 on Vaillant ecoTEC

Your boiler is currently performing a routine startup check to prepare for heating your home, and this is completely normal behavior.

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.

Technical description

Fan and pump running

DIY fix possible

No action is required.Wait a few moments for the boiler to complete its cycle.If the boiler remains in this state for longer than 15 minutes, toggle the power off and on again to clear the temporary hold.

Find a Gas Safe engineer
Search the official register →

Related fault codes

S. 0View →S. 1View →S. 2View →S. 3View →S. 4View →

Related guides you might find useful

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

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 →