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Vaillant F22 Fault Code Repair

Welcome to the fault-codes section of this site. The following table or page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. You may be guided through the fault finding sequence or steps, for rectifying your boiler with this fault code. Suggested repair solutions may be provided by a link to a repair page. NB Some fault codes are only applicable to a specific range of boilers only.

F22 Meaning

Safety switch-off: low water pressure. Shown on display as F.22


No pressure or water pressure too low in the boiler, water pressure sensor defective, cable to pump or water pressure sensor loose/not connected/defective

Solutions for F22 Fault code

1.Top up the pressure of the boiler or system using the internal filling loop if it is a combi boiler, otherwise using the external filling loop attached to the system. If you would like to know the correct pressure of the heating system see our page on Boiler Pressure . Also see instructions below on how to increase boiler pressure for vaillants.

2. The pressure sensor connection may have come out or become loose. Take the cable out, check it’s not broken and then re-insert back in.

3. Check that the pump connection is not loose. If necessary remove the connection from the connector, check and re-insert.

How to increase the pressure on a Vaillant boiler

In order to pressure a Vaillant boiler, see the following steps.

Locate the filling loop. This may be the integrated type under the boiler or external to the boiler, usually on combi boilers, but still possible that it’s located on the pipes further below the boiler or another part of the system.

Integrated Filling loop. Two white knobs. Turn them both to the open position to top up the system to the correct pressure, then turn both white knobs to the off position.

Vaillant Integrated Filling Loop image
Vaillant Integrated Filling Loop

External Filling loop. Usually 1 or 2 black knobs either side of a silver flexible hose, turn both to top up system.

External Filling Loop

Finally, you may have to reset the boiler to clear F22 fault code, if topping up the pressure does not immediately cause the boiler to begin working. In most cases topping up the pressure is enough to bring it back online.

Video – Pressurising Vaillant Ecotec Plus

Pressurising Vaillant Ecotec Plus boilers with internal filling loops. Your Ecotec Plus may also have an external filling loop, however it is perfectly ok to use the built in internal filling loop. We recommend in most cases a target system pressure between 1.2 and 1.4 bar whilst system is off.

Video – Pressurising Vaillant Ecotec Pro

Pressurising Vaillant Ecotec Pro boilers, or those with external filling loops. Ecotec pros don’t have a internal filling loop.This youtube video is provided by VaillantUK

Disclaimer: Information on this website is provided for informational purpose therefore we cannot accept liability for subsequent problems. All repair tasks should be carried out by qualified trades people. We may also receive commission payments when you are taken to external websites and complete purchases from third party sellers, once you leave our site, we cannot be held liable for your purchases.