Low
S.17 on Vaillant aquaPLUS

Your boiler is temporarily running the pump to move excess heat away from the hot water heat exchanger after use.

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

Pump over run (hot water operation)

DIY fix possible

Wait up to 20 minutes for the status code to change naturallyEnsure radiators are not all turned off at their valvesCheck that the boiler pressure gauge is between 1 and 1.5 bar

Find a Gas Safe engineer
Search the official register →

Related fault codes

S.07View →S.10View →S.13View →

Related guides you might find useful

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Radiators cold at the bottom

Sludge build-up — needs flushing, not bleeding.

Read →