Error code

Vaillant Boiler Fault Code F22

Last updated: 2 April 2026Boiler faults need a cautious approach

Quick answer

F22

medium severity

System water pressure is too low

First safe action

Check the pressure gauge against the manufacturer guidance in the manual.

Meaning

Vaillant boiler fault code F22 usually means the boiler has detected low system pressure and locked out to protect the heating circuit.

Likely causes

Pressure dropped below the normal operating range
Recent radiator bleeding or maintenance
Ongoing water loss from a leak

Safe first checks

Check the pressure gauge against the manufacturer guidance in the manual.
If the boiler allows user repressurising, follow only the official filling loop method.
Stop if pressure drops again quickly after topping up.

How to reset

Reset the boiler only after the pressure has been restored to the correct range.
Do not keep resetting if the pressure immediately falls again.

When to call an engineer

If pressure repeatedly drops or you notice leaks, arrange a qualified heating engineer.

Safety warning

Do not remove the boiler casing or attempt internal repairs. Use only the manufacturer-approved repressurising method, and book a qualified heating engineer if pressure keeps falling.

Useful hub links

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Related fault codes

F23 for Vaillant Boiler

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F27 for Vaillant Boiler

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F28 for Vaillant Boiler

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F29 for Vaillant Boiler

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F32 for Vaillant Boiler

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Relevant guides

Boiler Fault Codes: When to Stop and Call a Professional

Boiler issues need a more cautious approach than most white goods, especially where gas, combustion, or repeated lockouts are involved.

Frequently asked questions

Can I keep resetting a Vaillant boiler with F22?+

No. If F22 returns after one standard user reset, stop there and arrange a qualified engineer if the manual gives no safe next step.

Is F22 something I can repair myself?+

Boiler faults should be treated cautiously. Stay within the user checks in the manual, and leave gas, combustion, and internal boiler repairs to a qualified professional.