Vaillant Boiler F22 Error – What It Means & How to Fix It
Is your Vaillant boiler showing the F22 error code?
This means your boiler has low water pressure or there’s a problem with the pressure sensor.
We’ll explain what causes the F22 fault, how to fix it yourself safely, and when it’s time to call in a professional.
What Is the F22 Error Code?
The F22 error code is common across Vaillant boilers — especially in ecoTEC Pro, Plus, and combi models.
It means the water pressure in your central heating system is too low for the boiler to operate safely.
✅ F22 = Low system water pressure or pressure sensor fault
If pressure drops too low (typically below 0.5 bar), your boiler will shut down to prevent damage.
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Why Does My Vaillant Boiler Show F22?
Common causes:
Leaks in the system (radiators, pipes, or boiler)
Air in radiators causing imbalance
Recently bled radiators, losing water volume
Faulty pressure sensor or pump
How to Fix Vaillant F22 Error Code
DIY Fix: Repressurize Your Boiler
Follow these steps:
Turn off the boiler
Locate the filling loop underneath your boiler
Slowly open both valves until pressure reaches 1.2–1.5 bar
Close the valves and restart the boiler
⚠️ Still getting F22?
There may be a leak, airlock, or faulty sensor — you’ll need a Gas Safe engineer.
Need full technical info?
We got you here is a link for a manual,
👉 📄 Download the Official Vaillant ecoTEC Manual (PDF)
Includes pressure settings, fault codes (like F22), wiring diagrams, and troubleshooting steps.
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When to Call a Heating Engineer
Call a professional if:
- Repressurizing doesn’t work
- You’re losing pressure regularly
- You suspect a leak or sensor fault
🚨 Don’t risk damaging your boiler or voiding your warranty.
A Gas Safe registered engineer can fix F22 faults fast and safely
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FAQs
Q1: What does F22 mean on a Vaillant boiler?
It means low water pressure or a fault with the pressure sensor. The system shuts down to protect itself.
Q2: Can I fix the F22 error myself?
Yes, often you can repressurize the boiler using the filling loop. If the problem returns, call an engineer.
Q3: Is F22 dangerous?
It’s not dangerous but it does stop your heating and hot water. It should be dealt with quickly.
Q4: How much does it cost to fix F22?
DIY is free if it’s just low pressure. If parts need replacing (e.g., sensors), costs typically range from £70–£180.
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cliff Potter
Had problems with pressure dropping on…
Had problems with pressure dropping on boiler. Ryan came out fast and identified the problem and fixed it. We also mentioned concerns of smelling of gas which he promptly investigated and he detected a gas leak at the main meter. This was resolved immediately and we cannot thank him enough. We would highly recommend him. The fees were very reasonable. Both reliable and professional. We would definitely book him for any further work in the future. Thanks Cliff
Date of experience: 26 February 2022
steve clark
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My central heating boiler had a serious safety problem which, Ryan, diagnosed and fixed. The job was not an easy one. Removing the faulty part proved difficult because it was so damaged. But Ryan persevered and got my boiler safe and working efficiently. I will ask for him by name the next time my service is due.
Date of experience: 21 July 2023
David Haskell
GB
2 reviews
Excellent service. Ryan systematically diagnosed the fault in my combi boiler .& promptly .sent his engineer Mark to carry out the repair. Both Ryan & Mark were very competent, efficient, helpful & polite, I have no hesitation in recommending the company.
David Haskell