How much does it cost to fix Vaillant error code F22?

Typical repair cost for the Vaillant F22 fault is £0-120 including labour.

F22 High

Vaillant F22 Fault Code

Q: What does the Vaillant F22 fault code mean?

Your boiler has stopped working because the water pressure is too low for it to run safely.

The Vaillant F22 fault code means: your boiler has stopped working because the water pressure is too low for it to run safely.. It appears on 15 Vaillant models in our database.

Technical description: Not enough water in the system

What causes the Vaillant F22 fault?

This fault occurs when the internal sensors detect that there isn't enough water circulating through the boiler to operate safely. The most common reason is a slow leak somewhere in your radiator system or a failing component that has allowed pressure to drop below the minimum threshold. Without enough water, the boiler shuts down to prevent the heat exchanger from overheating.

This issue is frequently seen in autumn when homeowners turn their heating back on for the first time, as tiny leaks during the summer months can gradually drain the system pressure.

Typical repair cost £0-120 (including labour)

DIY fix possible

Check the pressure gauge on the front of the boiler; it is likely below 1 bar.Locate the external filling loop, which is usually a flexible silver hose under the boiler.Slowly open the tap valves on the hose until the gauge reaches 1.5 bar, then close them tightly.Reset the boiler to clear the fault code.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Vaillant models that show the F22 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Vaillant F22 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026