Low Information
73:1 to 73:6 on Viessmann Vitodens 050-W

Your boiler is notifying you that the hot water cylinder's circulation pump is running on a preset timed cycle to prevent legionella or keep the water warm, rather than responding to a specific heating demand.

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

During the time program 1x/h ON for 5 minutes up to 6x/h ON for 5 minutes

What causes this fault?

This is not a mechanical failure but rather a status notification triggered by the boiler's internal anti-legionella or comfort settings. It occurs when the control system activates the domestic hot water circulation pump for short, periodic bursts to keep water moving through the pipes. This ensures hot water is instantly available at the taps and prevents water from stagnating in the cylinder.

DIY fix possible

This is often a status notification rather than a breakdown.Check your hot water time program settings on the control panel.Ensure your legionella protection or DHW circulation pump settings match your daily needs.

Find a Gas Safe engineer
Search the official register →

Related fault codes

73:0View →73:7View →

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →