Vaillant Boiler F22 Fault Code and What It Means & How to Fix It

20/03/202520/03/2025

Estimated reading time: 4 minutes

The Vaillant F22 fault code is a low water pressure fault that prevents the boiler from operating properly. This error occurs when the system detects insufficient pressure, which can lead to heating and hot water failure. Maintaining the correct pressure is essential for your boiler to function efficiently.

What is Vaillant F22 Fault Code?

When your Vaillant boiler displays the F22 fault code, it indicates a low water pressure issue. This often stems from insufficient water in your heating system, typically caused by a leak. As the leak leads to a drop in boiler pressure, the F22 fault code is triggered. It’s crucial to address this issue promptly, as allowing the low pressure to persist can cause your boiler’s components to overwork, resulting in expensive repairs down the line.

Common Causes

Several common issues can lead to the F22 Error code, including:

Low Boiler Pressure: This is the most common cause of the F22 fault code.
No Heat: If your boiler can’t provide heat, the F22 fault code may appear.
No Hot Water: A lack of hot water is often a result of low pressure.
Leaks in the Boiler or Pipework: Leaks can cause a significant drop in pressure.
Hot Water Without Heat: If you have hot water but no heating, this could signal a pressure issue.

How to Fix F22 Fault Code on Your Vaillant Boiler

Here’s a step-by-step guide to help you resolve the F22 Fault Code:

Examine the Boiler’s Water Pressure Sensor

If you’re seeing the Vaillant F22 Fault Code, first check the Water Pressure Sensor. Your Vaillant boiler should ideally maintain a pressure of 1.5 bar. If the pressure is within this range and you’re still receiving the F22 Fault Code, the problem is likely with the sensor. You may need to replace it, and it’s best to consult with a heating engineer for assistance.

Check for Low Boiler Pressure

If the pressure in your boiler drops below 0.5 bar, the system will lock out. This typically happens when there’s a leak in your heating system. If the pressure has dropped this significantly, it’s crucial to locate and address the leak to prevent further issues and restore proper boiler function.

Check for Leaks

If you suspect a leak, carefully inspect your boiler, surrounding pipes, radiators, and towel rails. Even a small leak can cause a gradual drop in pressure. Check for signs of water leakage around joints and connections. If you can’t find the leak or fix it yourself, it’s time to call in a professional heating engineer to inspect your system further.

Increase Boiler Pressure

Once the leak is repaired, it’s time to top up your boiler’s pressure. If you’re comfortable doing this yourself, locate the external filling loop—a small hose at the bottom of your boiler. Open the valve and let water flow into the system until the pressure reaches the desired level (typically 1.5 bar). Once the pressure is set, close the valve securely.

Reset Your Boiler

After topping up the pressure, you’ll need to reset your boiler. Find the reset button, usually located near the control panel. Hold the reset button for a few seconds to initiate the reset sequence. This process may take a few minutes, after which your boiler should operate normally.

Still Having Trouble ?

If you’ve followed these steps and are still experiencing issues with the Vaillant F22 fault code, don’t hesitate to contact a qualified heating engineer. At Tyne and Wear, our team of experienced boiler specialists can help resolve any problems with your Vaillant boiler and ensure it runs efficiently.

Final Thoughts

The Vaillant F22 fault code on your Vaillant boiler is often caused by low water pressure, usually due to a leak in the system. By carefully examining the water pressure, checking for leaks, and topping up the pressure, you can often fix the issue yourself. However, if you’re unsure or if the problem persists, it’s always a good idea to call in a Professional Gas Engineer to avoid further complications.