Viessmann · Vitodens 050-W
74 boiler fault code
Vitodens 050-W types B0HA / B0KA
Get a Gas Safe engineer
Free. Enter your postcode.
What 74 means
74 indicates that system pressure is too low, locking out the burner and stopping central heating and domestic hot water.
Safe check
Switch the boiler off and allow it to cool. Use the filling loop to raise pressure to the value stated in the Viessmann guide, then restart once.
When to contact an engineer
The code returns after repressurising or pressure will not hold; arrange a Gas Safe registered engineer.
Safety notice
A boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, anyone feels unwell, or there is an unsafe flame, leave and call 0800 111 999 from outside.
Source and provenance
- Vitodens 050-W types B0HA/B0KA · 6194588 GB · Diagnosis table, p. 65
installation and service instructions
12/2022 · document 6194588 GB
- Viessmann How to repressurise a combi boiler
homeowner guide
Checked 30/09/2026; the online page publishes no revision
Renting? Report it to your landlord or housing provider first. They are responsible for gas safety and boiler repairs, and the repair should not cost you.
Did this fix it?
After: Repressurise the boiler