A Step-by-Step Guide to Solving the Vaillant F22 Fault Code

How to address the Vaillant F22 fault code, what it means, possible causes and how to fix it.

As a homeowner, there are few things more frustrating than waking up to find that your boiler has stopped working.

For safety, boilers shut down automatically when they encounter a problem. The display will show a fault code and this helps homeowners and heating engineers identify what the problem is and fix it.

If you see the Vaillant F22 fault code on your display, don’t panic: in this article, we’ll cover everything you need to know to fix this issue.

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Causes of the Vaillant F22 Fault Code

First, let’s start with the basics.

The Vaillant F22 fault code indicates that there is a problem with the water pressure in your boiler.

This can be caused by a few different factors, including a leak in your system or a malfunctioning pressure gauge.

Fortunately, this issue is relatively simple to diagnose and fix.

How to fix the F22 Fault Code

The first thing you should do is check your boiler’s pressure gauge.

If the gauge is showing a reading below 1 bar, then it’s likely that the problem is simply that your boiler’s water pressure is too low.

To fix this, you’ll need to top up your boiler’s water pressure.

To do this, you’ll need to locate your boiler’s filling loop.

This is a flexible hose with two tap handles that is usually located underneath your boiler.

Once you’ve found it, you can follow these steps to top up your boiler’s water pressure:

  1. Turn off your boiler and wait for it to cool down.
  2. Locate the two tap handles on your filling loop. These will usually be red or blue in colour.
  3. Turn both tap handles so that they are fully open.
  4. You should hear water flowing into your boiler. Keep an eye on the pressure gauge, and close the tap handles once the pressure reaches around 1.5 bar.
  5. Turn your boiler back on and check that the fault code has cleared.

What To Do If Repressurising Doesn’t Fix The F22 Fault Code

If the F22 fault code persists after topping up your boiler’s water pressure, then there may be a leak in your system.

This could be caused by a number of things, including a faulty valve or a damaged pipe.

In this case, it’s best to call in a professional heating engineer to diagnose and fix the issue.

Other causes of the F22 Fault Code

It’s worth noting that in some cases, the Vaillant F22 fault code can be caused by a problem with your boiler’s pressure sensor.

If this is the case, then replacing the sensor may be necessary to fix the issue.

However, this is a more complex repair that should only be attempted by a trained professional.

It’s worth noting that the Vaillant F22 fault code can cause your boiler to shut down, so it’s important to address the issue as soon as possible to avoid any disruption to your heating and hot water.

If after reading this guide, you’re still not sure or confident to fix the problem yourself, it’s always best to call in a certified heating engineer to ensure that the issue is diagnosed and repaired correctly.

Why is it important to call a heating company to fix the F22 fault code?

If you encounter the F22 fault code on your Vaillant boiler, it is essential to call a heating company to fix the problem. Here are a few reasons why:

  1. Safety: A drop in water pressure can cause the boiler to overheat and potentially become a safety hazard. It’s important to have a qualified heating engineer inspect the system to ensure that it’s safe to operate.
  2. Efficiency: A drop in water pressure can cause the boiler to work harder and less efficiently. By calling a heating company to fix the problem, you can ensure that your boiler is operating efficiently and effectively, which means you save in heating bills.
  3. Expertise: A qualified heating engineer will have the expertise and experience to diagnose the problem and recommend the appropriate solution. Attempting to fix the problem yourself can be dangerous and can cause further damage to your boiler.
  4. Warranty: If your boiler is still under warranty, attempting to fix the problem yourself could void the warranty. By calling a heating company to fix the problem, you can ensure that your warranty remains intact.

How can a heating company fix the Vaillant F22 fault code?

A qualified heating engineer will be able to diagnose the cause of the F22 fault code and recommend the appropriate solution. Here are some possible solutions:

  1. Fixing the water leak: If the F22 fault code is caused by a water leak, the heating engineer will need to locate and fix the leak. This may involve replacing a faulty valve, repairing a damaged pipe, or fixing a leaking radiator.
  2. Flushing the system: If the pipes in the system are blocked or restricted, the heating engineer may need to flush the system to remove any debris or scale build-up.
  3. Replacing faulty components: If the F22 fault code is caused by a faulty pressure gauge or pressure relief valve, the heating engineer may need to replace these components.


In conclusion, the F22 fault code on your Vaillant boiler indicates an issue with the low water pressure in the system.

If you see this code on your boiler’s display, the first step is to check your boiler’s water pressure and top it up if necessary.

If the F22 fault code persists, the cause could be a water leak, blocked pipes, faulty pressure gauge, or faulty pressure relief valve and these need to be fixed by a professional heating engineer.

By following the above steps, you can quickly and easily diagnose this issue and know what next steps to take, ensuring that your home stays warm and comfortable all year round.

Next Steps

When you experience a fault code on your Vaillant boiler, it’s important to take action quickly to avoid further damage to the boiler or your home.

Remember, attempting to fix the issue yourself can be dangerous, can cause further damage to the boiler as well as invalidate the manufacturer’s warranty.

Always seek advice from a qualified engineer who has the expertise and knowledge to diagnose and repair the issue safely and effectively.

If you have any further questions or concerns about the F22 fault code or your Vaillant boiler, contact us for help.

Book your appointment by contacting us today.

We cover locations in London, Watford, Hertfordshire and Middlesex.

Disclaimer: Please note that the information provided in this article is given in good faith and for educational purposes only. It is not intended to replace a diagnosis from a certified or trained gas central heating engineer. The use of this information is at your own risk, and we accept no liability for any damages or losses incurred as a result of relying on this information. It is always recommended to seek the advice of a qualified professional before attempting any repairs or maintenance on your gas central heating system.

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