Vaillant ecoTEC F27 fault code

Vaillant F27 fault code explained

One of the most common Vaillant boiler fault codes is the F27 or F.27 fault/error code.

If you have a Vaillant ecoTEC boiler there is a good chance you may experience this fault code at some point.

This fault code can cause your Vaillant boiler to stop working, leaving you without central heating or hot water.

The following video is a clip from a broken Vaillant ecoTEC Plus boiler displaying an F27 fault code.

If you look in the Vaillant ecoTEC installation manual under the F27 fault code it states the following;

“Safety switch-off: Flame simulation – Monitoring electrode reports an incorrect flame”.

There are some exceptions but a lot of the time the F27 will be pointing in the direction of a failing or failed printed circuit board(PCB).

On all boilers including the Vaillant ecoTEC range of boilers, they have a printed circuit board which controls every process that happens on the boiler.

When the printed circuit board on a Vaillant boiler detects a serious irregularity, it will usually shut down and display a fault code, making the end user aware of the issue as the boiler also stops working.

The F27 fault code is related to the F61 fault code and the F62 fault code.

Sometimes you may see the F27, F61 and/or F62 fault code appearing at different times after the boiler has been reset.

On a Vaillant ecoTEC boiler if you are seeing these different fault codes at different times it is usually indicative of imminent printed circuit board failure.

This is sometimes because the transformers on the printed circuit board start to fail which affects the voltage on the circuit board.

As such the printed circuit board can detect this and will often display a fault code as an indicator as to what might be wrong.

Although the F27 fault code will more than likely be related to the printed circuit board, it is possible that something else like a wiring harness could be causing the issue.

Which is why it is important to get a suitable Gas Safe registered heating engineer with experience on Vaillant ecoTEC boilers, otherwise you could waste money fitting parts to your boiler that are unnecessary.

When to call a gas engineer to fix your boiler

If you are experiencing the F27 fault code on your Vaillant boiler, it is important to take action as soon as possible.

While some issues can be resolved by homeowners themselves, others require the expertise of a qualified Gas Safe registered heating engineer.

Because the F27 fault code can be caused by several different faulty parts, it is extremely important to get a suitable heating engineer with experience on Vaillant ecoTEC boilers, otherwise you could end up wasting money fitting parts to your boiler that are unnecessary.

Often for a while you will be able to reset your boiler if its showing and F27 fault, but in general this is just a short term solution and usually your boiler will stop working altogether at some point, leaving you without hot water and heating.

So it usually best to get a qualified Vaillant trained heating engineer to have a look at your boiler at your earliest convenience.

How to prevent the F27 fault code

A lot of the time certain faults on a Vaillant ecoTEC boiler can be prevented with regular annual servicing and maintenance.

However this is often not generally possible with the F27 fault code as often it is caused to components on the boiler which are non serviceable items.

The printed circuit board for example, is programmable but is a non serviceable part.

While servicing your boiler a good engineer with experience working on Vaillant ecoTEC boilers might be able to tell if your circuit board is coming to the end of its life.

As such they can recommend replacing the printed circuit board as a preventative maintenance measure, to ensure your boiler doesn’t stop working with an F27 fault code when you need it most – like in the middle of winter.

First generation Vaillant ecoTEC boilers made from 2005 – 2011, will often exhibit certain behaviours when the printed circuit board is starting to fail – good Vaillant trained engineers know exactly what to look for!

Vaillant ecoTEC boilers affected by the F27 fault code

The F27 fault code on Vaillant ecoTEC boilers can affect any combination, system or heat-only boiler.

So this fault code can be found on any Vaillant ecoTEC Pro combination boilers, any ecoTEC plus 800 Series combination boilers, any ecoTEC plus 600 series system boilers and any 400 series heat-only boilers.

Below is a list of ecoTEC boilers affected by the F27 fault code;

• ecoTEC Pro 24 and ecoTEC Pro 28 natural gas combination boilers
• ecoTEC Plus 800 Series 824, 828, 831, 837 and 937 natural gas combination boilers
• ecoTEC Plus 800 Series 825, 832, 835, 838 and 938 natural gas combination boilers
• ecoTEC Plus 600 Series 612, 615, 618, 624, 630 and 637 natural gas system boilers
• ecoTEC Plus 400 Series 415, 418, 428 and 438 natural gas heat-only boilers

Frequently asked questions:

Is my boiler showing an F27 fault code worth repairing ?

Yes most of the time your broken Vaillant ecoTEC boiler displaying an F27 fault code will be worth repairing. Obviously the cost to repair your boiler will be determined by which parts need to be replaced.

You would need a competent, Gas Safe registered heating engineer to have a look at your boiler and make an assessment to determine exactly which parts might need to be replaced.

Before replacing your boiler it is always worth getting a suitable Gas Safe registered heating engineer, with experience working on Vaillant ecoTEC boilers, to make an assessment of your boiler so you can determine whether it is worth fixing not.

Can I repair the F27 fault code myself?

No unfortunately not, in most cases repairing the F27 fault code will require removing the cover of your boiler to replace parts which you are not legally allowed to do unless you are a Gas Safe registered heating engineer.

You may be able to reset your boiler and it may work for some time.

Is the F27 fault code dangerous?

No the F27 fault code is not inherently dangerous. Modern Vaillant boilers are designed with fail safes in place to make sure that the boiler will only work if it safe to do so.

In general if you have an F62 fault code you will be able to reset your boiler for a period of time but then it will probably stop working altogether.

The F27 fault code is often indicative of an issue with the printed circuit board, which is the most important part of the boiler as it controls everything.

As such if your boiler is coming up with an F27 fault code, the best thing to do it get it repaired at your earliest convenience, by a suitable Gas Safe registered heating engineer – ideally one that has experience working on Vaillant boilers.