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F61 Vaillant Boiler Fault Code Explained [And What to Do Next]

Are you seeing F61 on your Vaillant boiler display panel, and has your boiler locked out? Then you’re in the right place — this guide will help you figure out what the error code means and what to do next.

Why You’re Seeing F61 on Your Vaillant Boiler

Put simply, the Vaillant F61 fault code points to a gas valve fault. This means that pressing the reset button on your Vaillant EcoTEC won’t help — you’ll need to book in a Gas Safe engineer to find and fix the fault, as they’re the only people that are qualified to work on gas appliances.

Why Your Boiler Locks Out When Displaying the F61 Fault Code

A boiler with a gas fault is potentially dangerous. Your PCB (Printed Circuit Board) monitors a range of sensors to determine whether your boiler is working safely and efficiently. If it detects an issue with the gas supply, it will lock the boiler out as a precaution, and display “F61” on the screen.

What Causes the F61 Vaillant Fault Code

If you’re seeing F61 on your Vaillant boiler’s display, the most likely explanation is that the gas valve has become stuck or is completely seized. Since valves are mechanical in nature, this is an entirely natural occurrence.

That said, in other cases, the problem could relate to wiring issues or even a communication error with the boiler’s main circuit board.

  1. Stuck & Seized Valves

If the Vaillant F61 error you’re getting signifies a stuck or seized valve, there could be 2 complications. If the valve is partially stuck open, it could be letting gas into the combustion chamber when it shouldn’t; this is potentially dangerous. And when it’s working on the flip side (stuck partially closed), it’s starving your boiler of gas.

Luckily, in most cases, these valves can be freed. As we’ve mentioned above, you’ll need to book a Gas Safe engineer or call your boiler cover policy provider and they’ll be able to asses the situation. If the valve can’t be completely freed, it’s likely they’ll suggest a replacement.

  1. Problems With Wiring and Connections

Another common reason you may be seeing the Vaillant boiler F61 fault code has to do with wiring problems and connection faults. 

Wiring can easily come loose because boiler parts such as the pump and fan vibrate. Likewise, connections can be come damaged, sometimes due to old age, or suffer a short circuit because of leaks.

Small issues with wiring and connections (and even water damage) can be fixed and secured. But if in doubt, your Gas Safe engineer will simply replace the valve (sometimes this is less than the cost of labour for boiler repair).

  1. Faulty Gas Valve Assembly

If your Vaillant F61 error points to a faulty gas valve, bad news — you may have to replace the valve altogether. Unfortunately, not all gas valves can be fixed; sometimes, the combination of wear and damage means that fixing the component isn’t cost effective.

Your boiler engineer will be able to test the valve and determine if this is the case. If so, unfortunately a replacement is going to be needed.

  1. Printed Circuit Board Fault

We’ve seen instances where the Vaillant F61 fault is nothing to do with the gas valve, even though that is the stated cause.

If your engineer is confident the valve isn’t the problem, then it’s likely an issue with the wiring harness that connects the gas valve to the PCB.

The PCB is the control hub for your boiler, and all electronic parts rely on it for signals, so they know exactly when to operate (and when to cease operation). If there’s a problem here, your boiler will simply lockout.

Unfortunately, the cost of a PCB replacement can sometimes be as much as £500.

If your boiler is out of warranty and needing repairs of this magnitude, in general, it makes sense to consider a replacement (read our detailed boiler installation cost guide here).

You can get on-screen prices for a replacement boiler here in less than 90-seconds.

Here’s the Cost to Replace Your Boiler Gas Valve

As we’ve mentioned above, in some scenarios you can fix your boiler gas valve. But, if your Gas Safe engineer thinks there’s even the slightest chance of the fault persisting, you’ll need to replace it instead.

The overall cost of a replacement will be in the region of £300 (depending on the boiler model).

If you’re frequently getting other error codes, or the engineer finds that your boiler and other parts (such as the fan, pump, and PCB) are on their way out, it might be time to consider a replacement boiler instead of a repair.

You can get great deals on boilers through Heatable, one of the most affordable online boiler installers in the United Kingdom. All you need to do is fill out a simple on-screen form; it takes less than 90-seconds, and you don’t have to answer any personal questions.

Once you’ve supplied some key information about your central heating setup, Heatable will return a range of fixed-price quotes for boiler models for any budget.

Heatable boiler installations

FAQs About the Vaillant Boiler F61 Error Code

As we prepare to wrap up, we will answer a few common queries about the F61 code on Vaillant boilers.

What does F61 mean on a Vaillant boiler?

On Vaillant boilers, the F61 error code means that the gas valve is not functioning properly, or the boiler components aren’t communicating as they should be. Such a fault could occur for a variety of reasons:

  • The valve has seized
  • Wiring problems
  • Malfunctioning gas valve
  • Faulty printed circuit board

To find out the true root cause behind the F61 code, you should get a Gas Safe engineer to inspect your boiler.

How do I increase the pressure on my Vaillant boiler?

The easiest way to increase the pressure on a Vaillant (or any other boiler, really), is to top up your boiler via the filling loop. You can read more about the boiler repressurisation procedure here.

However, note that repressurising a boiler without first fixing the cause of low pressure is just a temporary solution. Since low boiler pressure is typically caused by a leak somewhere in the heating system, the pressure will keep dropping until you’ve fixed the leak.

What do I do if my boiler pressure is too low?

In 99% of cases, low boiler pressure is caused by a leak in the boiler or the central heating system. On rare occasions, a faulty pressure sensor may be the culprit.

Typically, if your boiler pressure is low, you’ll want to look for a leak and try to get it fixed. The leak may be anywhere in the system, not necessarily the boiler itself.

Once you’ve fixed the leak, you can top up the boiler via the filling loop until the pressure returns to normal levels.

How do I reset my Vaillant boiler?

Resetting a Vaillant boiler is relatively straightforward. Here’s what you do:

  1. Find the reset button — it will have a flame, flashing light, or a cross. The boiler manual should have an image of this button for your reference.
  2. Press and hold the button for 3-5 seconds.
  3. Wait for the boiler to reset — this may take several minutes.

In some cases, a Vaillant boiler may take more than one attempt to reset. However, if you’re still not having luck after 3 attempts, it probably means that the underlying issue has not been resolved and your boiler is still faulty. If this is the case, you should contact a Gas Safe heating engineer to inspect and repair your boiler.

What does F64 mean on my boiler?

The F64 signifies an electrical issue with a Vaillant boiler. More specifically, the F64 typically relates to:

  • Wiring issues
  • Faulty thermistors on the flow and return pipe
  • Printed circuit board problems

Given the complex nature of such a fault (and a challenging diagnostic process), it’s always best to get a professional to investigate the F64 fault.

What’s Next?

Still getting the Vaillant F61 fault code? Or is your Vaillant boiler showing more than one fault code and your engineer can’t find the problem?

Check out our guide to other Vaillant Boiler problems, or directly check out what the f75 code error means and the f28 fault code.

Or, drop us a line via our contact form and we’ll do our best to help you out.

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