Low
S.02 on Vaillant ecoTEC exclusive

Your boiler is simply preparing its internal pump before starting the process of heating your radiators; this is a normal operational status, not a fault.

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

Heating mode: Pump pre-run

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer
Search the official register →

Related fault codes

S.00View →S.01View →S.03View →

Related guides you might find useful

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

Radiators cold at the bottom

Sludge build-up — needs flushing, not bleeding.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →